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2012

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Articles 5941 - 5970 of 6303

Full-Text Articles in Engineering

Modulation Of Morpho-Functional Characteristics Of Astrocytes Using Chemically-Functionalized Water-Soluble Single-Walled Carbon Nanotubes, Manoj K. Gottipati Jan 2012

Modulation Of Morpho-Functional Characteristics Of Astrocytes Using Chemically-Functionalized Water-Soluble Single-Walled Carbon Nanotubes, Manoj K. Gottipati

All ETDs from UAB

In this thesis, I report the use of chemically functionalized water-soluble single-walled carbon nanotubes (ws-SWCNTs) for the modulation of morpho-functional characteristics of astrocytes. When added to the culturing medium, ws-SWCNTs were able to make astrocytes larger and stellate/mature, changes associated with the increase in glial fibrillary acidic protein immunoreactivity. Thus, ws-SWCNTs could have more beneficial effects at the injury site than previously thought; by affecting astrocytes, they could provide for a more comprehensive re-establishment of the brain computational power.

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Nanographene Reinforced Carbon/Carbon Composites, Dhruv Bansal Jan 2012

Nanographene Reinforced Carbon/Carbon Composites, Dhruv Bansal

All ETDs from UAB

Carbon/Carbon Composites (CCC) are made of carbon reinforcement in carbon matrix and have high thermal stability and fatigue resistance. CCC are used in nose cones, heat shields and disc brakes of aircrafts due to their exceptional mechanical properties at high temperature. The manufacturing process of CCC involves a carbonization stage in which unwanted elements, except carbon, are eliminated from the polymer precursor. Carbonization results in the formation of voids and cracks due to the thermal mismatch between the reinforcement and the matrix and expulsion of volatiles from the polymer matrix. Thermal cracks and voids decrease the density and mechanical properties …

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Monitoring Arm Use In Daily Life Via Rfid Tracking Of Household Objects, Joydip Barman Jan 2012

Monitoring Arm Use In Daily Life Via Rfid Tracking Of Household Objects, Joydip Barman

All ETDs from UAB

After stroke, capacity to complete tasks in the treatment setting with the moreaffected arm is an unreliable index of actual use of that extremity in daily life. Available objective methods for monitoring real-world arm use rely on placing movement sensors on patients. These methods provide information on amount but not type of arm activity, e.g., functional vs. nonfunctional movement. This paper presents an approach that places sensors on patients and household objects, overcoming this limitation. An accelerometer and the transmitter component of a radio-frequency proximity sensor are attached to objects; the receiver component is attached to the arm of interest. …

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Wind Resistance Of Composite Structural Insulated Panels (Csips), Li Dong Jan 2012

Wind Resistance Of Composite Structural Insulated Panels (Csips), Li Dong

All ETDs from UAB

Extreme windstorms are frequent and destructive natural hazards in the United States. Each wind disaster proves that traditional wood houses are too fragile to withstand high air pressures. The proposed Composite Structural Insulated Panels (CSIPs) are made of a low-cost, thermoplastic orthotropic glass/poly-propylene (glass-PP) laminate as the face sheet and expanded polystyrene (EPS) foam as the core, with a high face sheet/core moduli ratio. In order to evaluate the wind-resistance of CSIPs, panels with cores of 16 kg/m3 (1 PCF) and 48 kg/m3 (3 PCF) density were tested at the University of Florida. Stepwise and dynamic simulated wind pressure was …

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Engineering Of Pulsed Laser Deposited Calcium Phosphate Biomaterials In Controlled Atmospheres, Saulius Edmundas Drukteinis Jan 2012

Engineering Of Pulsed Laser Deposited Calcium Phosphate Biomaterials In Controlled Atmospheres, Saulius Edmundas Drukteinis

All ETDs from UAB

Synthetic calcium phosphates (CAP) such as hydroxyapatite (HA) have been used as regenerative bone graft materials and also as thin films to improve the integration of biomedical implant devices within skeletal tissue. Pulsed laser deposition (PLD) can deposit crystalline HA with significant adhesion on titanium biomaterials. However, there are PLD processing constraints due to the complex physical and chemical interactions occurring simultaneously during PLD, which influence ablation plume formation and development. In this investigation PLD CAP films were engineered with a focus on novel decoupling of partial pressure of H2O (g) (P(H2O)) from total background pressure, in combination with substrate …

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Tribology, Uv Degradation, And Structure-Property-Processing, John Tipton Jan 2012

Tribology, Uv Degradation, And Structure-Property-Processing, John Tipton

All ETDs from UAB

Nanoscale reinforcements offer the possibility of coupling the already proven high strength to weight properties of polymer matrix composites with additional multifunctional properties such as electrical conductivity, thermal conductivity, unique optics, UV/IR radiation absorption, and enhanced wear resistance. This work presents materials based on detonation nanodiamonds dispersed in two types of polyethylene. The work begins with an understanding of nucleation phenomena. It was discovered through isothermal kinetics using differential scanning calorimetry that nanodiamonds act as nucleating agents during polyethylene crystallization. A processing technique to disperse nanodiamonds into very viscous ultra-high molecular weight polyethylene was developed and analyzed. These composites were …

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Optimization Of A Biomimetic Poly(Lactic Acid) Ligament Scaffold, Andrew F. Uehlin Jan 2012

Optimization Of A Biomimetic Poly(Lactic Acid) Ligament Scaffold, Andrew F. Uehlin

All ETDs from UAB

The anterior cruciate ligament (ACL) is the most commonly injured ligament of the knee, often requiring orthopedic reconstruction using autograft or allograph tissue, both with significant disadvantages. As a result, tissue engineering an ACL replacement graft has been heavily investigated. The present study attempts to replicate the morphology and mechanical properties of the ACL using a nanomatrix composite of highly-aligned poly(lactic acid) (PLA) fibers with various surface and biochemical modifications. Additionally, this study attempts to recreate the natural mineralization gradient found at the ACL enthesis onto the scaffold, capable of inducing a favorable cellular response in vitro. Unidirectional electrospinning was …

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Mechanical Properties Of Long Carbon Fiber Reinfroced Thermoplastic (Lft) At Elevated Temperature, Qiushi Wang Jan 2012

Mechanical Properties Of Long Carbon Fiber Reinfroced Thermoplastic (Lft) At Elevated Temperature, Qiushi Wang

All ETDs from UAB

Long fiber reinforced thermoplastics (LFT) possess high specific modulus and strength, superior damage tolerance and fracture toughness and have found increasing use in transportation, military, and aerospace applications. However, one of the impediments to utilizing these materials is the lack of performance data in harsh conditions, especially at elevated temperature. In order to quantify the effect of temperature on the mechanical properties of carbon fiber reinforced thermoplastic composites, carbon fiber PAA composite plates containing 20% and 30% carbon fiber were produced using extrusion/compression molding process and tested at three representative temperatures, room temperature (RT 26°C), middle temperature (MID 60°C) and …

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Processing And Evaluation Of Long Fiber Thermoplastic Composite Plates For Internal Fixation, Paul Benjamin Warren Jan 2012

Processing And Evaluation Of Long Fiber Thermoplastic Composite Plates For Internal Fixation, Paul Benjamin Warren

All ETDs from UAB

The metallic plates used in internal fracture fixation may have up to ten times the elastic modulus of normal bone tissue, causing stress shielding-induced osteopenia in healed bone that can lead to re-fracture after plate removal and prolonged and painful recovery. Thermoplastic polymer matrix composites reinforced with long carbon fiber are promising alternative materials for internal fixation plates because they may be produced with relative ease and be tailored to have specific mechanical properties, alleviating the stress shielding problem. Long carbon fiber-reinforced polyetheretherketone (LCF PEEK) plates were produced using the extrusion / compression molding process. Static flexural testing determined that …

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Computational Investigation Of Drag Reduction With A Rear Flap On Trucks, Yangyang Hu Jan 2012

Computational Investigation Of Drag Reduction With A Rear Flap On Trucks, Yangyang Hu

All ETDs from UAB

Computational fluid dynamic (CFD) simulations of the steady state Reynolds-Averaged Navier-Stokes (RANS) equations using the second order k — ω turbulence model were performed to investigate the Drag Coefficients (Cd) of the Class 8 trucks under different geometric configurations. The reduction rates of aerodynamic drag using several add-on devices such as base flap, boat tail, underbody skirt, and tractor-trailer gap are investigated through the CFD simulations. Moreover, simulations by using different lengths and angles of the base flap and boat tail were conducted; the comparison indicates that the base flap design is more effective for the drag reduction. The optimized …

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Assessment Of Transit Oriented Development Impacts, Md Shah Imran Jan 2012

Assessment Of Transit Oriented Development Impacts, Md Shah Imran

All ETDs from UAB

The recent interest in smart growth, livable communities, and sustainability creates new opportunities for the adoption, expansion, and enhancement of transit services in communities across the U.S. Given that promoting livability and alternative modes is a key priority in the U.S. DOT's agenda, research on economic impacts from integration of transit is both timely and essential. This is important as many of the possible gains from such integration are not fully understood and properly measured to date, such as the related health and quality of life benefits. This thesis analyzes the economic impacts from the implementation of a transit improvement …

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Travel Time Reliability Under Varying Freeway Operating Conditions, Md Saidul Islam Jan 2012

Travel Time Reliability Under Varying Freeway Operating Conditions, Md Saidul Islam

All ETDs from UAB

The performance of the transportation sector is popularly regarded as one of the key indicators of a nation's economic development. Travel time reliability is of paramount importance to the transportation sector performance as it relates to quality transportation network operation, improved traveler satisfaction, and on-time arrival of shipments of goods. Travel time reliability refers to the consistency in travel times over the day or across days. The objective of this thesis is to identify measures and methods appropriate to measure travel time reliability; and apply those methods to study the reliability of travel time along urban freeway corridors under varying …

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Forensic Facial Reconstruction Using Computational Approach, Wenzhen Jia Jan 2012

Forensic Facial Reconstruction Using Computational Approach, Wenzhen Jia

All ETDs from UAB

Forensic facial reconstruction is an application of forensic anthropology. It is a process of recreating the face of a human being based on skull remains. The process of recreating faces can be used to identify otherwise unknown individuals or to reconstruct faces of historical figures, such as the famous effort of reconstructing King Tut in 2005. There are many approaches to perform facial reconstruction in both two-dimensional (2-D) and three-dimensional (3-D). In 2-D cases, an artist works from photos of the skull and sketches the facial features based on his or her scientific training and artistic intuition. In 3-D cases, …

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Wear Of Nanofilled Dental Composites In A Newly-Developed In Vitro Testing Device, Nathaniel C. Lawson Jan 2012

Wear Of Nanofilled Dental Composites In A Newly-Developed In Vitro Testing Device, Nathaniel C. Lawson

All ETDs from UAB

Purpose In vivo wear of dental composites can lead to loss of individual tooth function and the need to replace a composite restoration. To evaluate the wear performance of new and existing dental composites, we developed a novel system for measuring in vitro wear and we used this system to analyze the mechanisms of wear of nanofilled composite materials. Methods: A modified wear testing device was designed based on the Alabama wear testing machine. The new device consists of: 1) an antagonist which is lowered to and raised from the composite specimen by weight loading, 2) a motorized stage to …

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Design Of An Underground Storage Tank Involving Water Collection For Water Reuse To Irrigate The Campus Green Area Of The Uab Campus, Zhuo Li Jan 2012

Design Of An Underground Storage Tank Involving Water Collection For Water Reuse To Irrigate The Campus Green Area Of The Uab Campus, Zhuo Li

All ETDs from UAB

The UAB Campus Recreation Center is located in the Birmingham city block whose boundaries are University Blvd., 10th Avenue South, 14th Street South, and 16th Street South. The water supply of the UAB Campus Recreation Center is based on a natural underground water source, which is use such needs as pool water. The underground water is continuously pumped from its foundation in order to avoid flooding the basement of the Recreation Center. As a result, in addition to the water usage of the Recreation Center, the additional water pumped underground could be utilized to irrigate the campus green area. A …

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Multiscale Modeling Of The Mouse Femur, Shannon Lisenbee Jan 2012

Multiscale Modeling Of The Mouse Femur, Shannon Lisenbee

All ETDs from UAB

This paper seeks to advance the knowledge base for bones and how they respond to mechanical stimuli through the use of multiscale modeling. First, a simple but effective approach for segmenting bone from computed tomography images using MATLAB is presented. Using edge detection and gradient operators to identify areas of bone within an image allows for much more accurate and consistent bone segmentation than simpler techniques like thresholding. This technique is applied to the femur of a female mouse for use in further modeling and testing. Next a representative volume element (RVE) for lamellar cortical bone is created based on …

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Modeling And Multi-Objective Optimization For Energy-Based Target Localization Using Wireless Sensor Networks, Zhenxing Luo Jan 2012

Modeling And Multi-Objective Optimization For Energy-Based Target Localization Using Wireless Sensor Networks, Zhenxing Luo

All ETDs from UAB

This dissertation focuses on energy-based target localization in wireless sensor networks (WSNs). A WSN consists of a fusion center and a large number of sensors. The fusion center localizes a target using a maximum likelihood estimation (MLE) method based on decisions received from sensors whose positions are known. However, several factors may degrade localization performance, including imperfect communication channels, sensor faults, sensor position uncertainty, and sensor sleep. Localization performance may be improved if these factors are accounted for in the MLE framework. In this dissertation, models were developed that describe how localization performance is affected by imperfect communication channels, multi-hop …

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The Effects Of Venlafaxine On Functional Recovery Following Spinal Cord Injury, Don E. Mccormick Jan 2012

The Effects Of Venlafaxine On Functional Recovery Following Spinal Cord Injury, Don E. Mccormick

All ETDs from UAB

Spinal cord injury (SCI) can significantly alter a person's physical and psychological health over their lifetime. Depression in persons with SCI is often treated with antidepressants which alter serotonergic and adrenergic signaling, both regulators of plasticity. However, the effects of antidepressants functional recovery after SCI have never been evaluated. Therefore, we hypothesize that antidepressant therapy would alter functional recovery and neuropathic pain behaviors in a SCI rodent model. The aim of this study was to evaluate the effects of venlafaxine (VEN) administration on functional recovery in the rehabilitation setting using a SCI rodent model. Adult male Sprague-Dawley rats received a …

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An Information Theoretical Modeling And Analysis Of Systems, Bunyamin Ozaydin Jan 2012

An Information Theoretical Modeling And Analysis Of Systems, Bunyamin Ozaydin

All ETDs from UAB

The growth of the service industry also comes with problems and complications because of its inherent error proneness. As the complexity of systems increases, whether the system of interest is a service product or a natural phenomenon, it only proves that there is always a need for improved modeling approaches. In this study, we approach systems from an information theoretical perspective. More specifically, we model systems by noisy communication channels and analyze them by a structure of relationships whose elements are commonly used analysis tools in science and engineering. We call this modeling approach and the structure of relationships it …

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Connexin 43 Remodeling Contribute To Slowed Conduction Velocity In An Irreversible Arrhythmogenic Canine Model Of Non-Ischemic Heart Failure, Jiajie Yan Jan 2012

Connexin 43 Remodeling Contribute To Slowed Conduction Velocity In An Irreversible Arrhythmogenic Canine Model Of Non-Ischemic Heart Failure, Jiajie Yan

All ETDs from UAB

Heart failure is associated with a high mortality due to ventricular tachycardia leading to ventricular fibrillation that could arise from impaired conduction velocity. Myocardial conduction relies on intercellular coupling maintained primarily by the gap junction protein connexin43. The objective of this research is to assess the correlation between connexin43 remodeling and altered conduction in our novel irreversible and arrhythmogenic HF large animal model that mimics human heart failure. A novel heart failure canine model was established with combined strategy of creating aortic insufficiency and aortic constriction. We measured conduction velocity in heart failure and control left ventricular epicardium (n=5, 5) …

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Effects Of Segmented Shield Wires On Signal Attenuation Of Power-Line Carrier Channels On Overhead Transmission Lines, Shanshan Yang Jan 2012

Effects Of Segmented Shield Wires On Signal Attenuation Of Power-Line Carrier Channels On Overhead Transmission Lines, Shanshan Yang

All ETDs from UAB

Shield wire segmentation has been used for quite some time as an effective method for reducing transmission line power losses, with most segmented shield wire applications on extra high voltage lines utilizing phase-to-phase power-line carrier (PLC) coupling. However, as transmission system efficiency becomes more of a priority, some utilities may consider applying segmented shield wires to lower voltage lines, such as 115-kV and 230-kV lines, which most often utilize single phase-to-ground PLC coupling. Thus, knowledge of the effects of segmented shield wires on PLC signal attenuation for various coupling methods would be useful to relay engineers. Previous work in this …

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Effect Of Increasing Truck Weight On Bridges, Denson Yates Jan 2012

Effect Of Increasing Truck Weight On Bridges, Denson Yates

All ETDs from UAB

The issue of increasing the gross vehicle weight limit on the interstate highway system has been debated on the local and federal levels. The driving forces for and against this topic cover a broad spectra ranging from economic benefits to public safety. The University Transportation Center of Alabama is sponsoring this study assessing the force effect that bridges experience when travelled by vehicles with a 97,000-lb gross vehicle weight (GVW). The maximum internal shear and moment caused by two proposed trucks (97-S and 97-TRB) are compared to effects from three base models: design live loadings from the American Association of …

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Simulation Of Bridge Weigh-In-Motion System Integrated With Bridge Safety, Zhisong Zhao Jan 2012

Simulation Of Bridge Weigh-In-Motion System Integrated With Bridge Safety, Zhisong Zhao

All ETDs from UAB

Bridge weigh-in-motion system (B-WIM) testing is a popular technology in bridge applications. The B-WIM system can track extensive information about loading conditions to which bridges are subjected, and engineers can evaluate the responses of bridges and assess their performance relative to the safety index and serviceability. Currently, the USA, significant numbers of bridges are considered defective and are eligible for retrofits and replacement. Optimized safety evaluation of old and defective bridges is urgent in response to reduced government funding for infrastructure improvements. To conduct safety evaluations of existing bridges without interrupting traffic, the B-WIM system is the first choice for …

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Effect Of Childhood Obesity On Risk Of Pelvic Bone Fracture In Simulated Sideways Fall, Min-Heng Hsieh Jan 2012

Effect Of Childhood Obesity On Risk Of Pelvic Bone Fracture In Simulated Sideways Fall, Min-Heng Hsieh

All ETDs from UAB

Since the number of obese children in the U.S. has been increasing, the question arises whether obese children could be at higher or lower risk compared to nonobese children. The objective of this research was to investigate the risk of pediatric pelvic bone fracture in sideways falls using computational modeling and simulation considering various levels of obesity. Two sets of models were developed and tested. The first set was body component models. Several 10-year-old pelvis-femur complex models were developed. The models included biological soft tissue layers to reflect various levels of obesity, and they were validated against published experimental data. …

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Model System Using Controlled Receptor Expression For Molecular Ultrasound Imaging Applications, Reshu Saini Jan 2012

Model System Using Controlled Receptor Expression For Molecular Ultrasound Imaging Applications, Reshu Saini

All ETDs from UAB

Ultrasound is a noninvasive, inexpensive imaging modality used to characterize biological tissues. Targeted contrast-enhanced ultrasound imaging is an emerging preclinical strategy which uses contrast agents for characterization of biological processes on a molecular level. These microbubble agents are lipid shelled micron-sized particles that have the capability to be coated with ligands such as antibodies or small peptides in order to bind to their target receptors. Molecular ultrasound imaging, using these targeted contrast agents, allows for a quantitative assessment of molecular targets with a high sensitivity. Although this technique is in preclinical research, further advances in contrast agent design and potential …

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Mechanical Analysis Of Bacterial Nanocellulose For Biomedical Applications, Joseph Mathias Schwertz Jan 2012

Mechanical Analysis Of Bacterial Nanocellulose For Biomedical Applications, Joseph Mathias Schwertz

All ETDs from UAB

Bacterial nanocellulose (BNC) is a biopolymer that has been used in a variety of applications ranging from speaker diaphragms to biomedical products. Created by micro-organisms like Gluconacetobacter xylinus, BNC is composed of long cellulose fibers in a highly crystalline hydrogel. Recent interest in BNC based materials has led to the discov-ery of several cultivation and post-processing treatments that have enabled researchers to control the mechanical and structural properties of the hydrogel. Three BNC treatments were mechanically evaluated through tensile testing. Ten-sile tests were conducted using dogbone shape test strips and a video extensometer. Phys-ical compression of a BNC hydrogels not …

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Construction Of Polynomials And Linear Weight Calculation For Weno Schemes, Jacob Alan Nelson Jan 2012

Construction Of Polynomials And Linear Weight Calculation For Weno Schemes, Jacob Alan Nelson

All ETDs from UAB

Many applications of computational fluid dynamics (CFD) require higher order spatial accuracy to resolve the flow field. A few examples of these complex flows include heat transfer problems associated with hypersonic flows, flapping wing simulations, turbo-machineries, rotorcrafts, aero-acoustic problems, and transition to turbulence. Methods being used within the CFD community to achieve higher order spatial accuracy include discontinuous Galerkin schemes, weighted essentially non-oscillatory schemes (WENO), and spectral volume (SV) schemes. Complex flow problems involving complex geometries may necessitate the use of generalized grids for the discretization of the domain. Generalized grids contain elements of multiple types and allow for a …

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Electrospun Carbon Nanofibers Decorated With Various Amounts Of Electrochemically-Inert Nickel Nanoparticles For Use As High-Performance Energy Storage Materials, Liwen Ji, Zhan Lin, Mataz Alcoutlabi, Ozan Toprakci, Yingfang Yao, Guanjie Xu, Shuli Li, Xiangwu Zhang Jan 2012

Electrospun Carbon Nanofibers Decorated With Various Amounts Of Electrochemically-Inert Nickel Nanoparticles For Use As High-Performance Energy Storage Materials, Liwen Ji, Zhan Lin, Mataz Alcoutlabi, Ozan Toprakci, Yingfang Yao, Guanjie Xu, Shuli Li, Xiangwu Zhang

Mechanical Engineering Faculty Publications

Carbon nanofibers decorated with various amounts of electrochemically-inert metallic nickel nanoparticles are synthesized through electrospinning and carbonization processes. The morphology and composition of Ni nanoparticles in carbon nanofibers are controlled by preparing different nanofiber precursors. The lithium-ion battery performance evaluations indicated that the content of electrochemically-inert Ni nanoparticles in carbon nanofibers has a great influence on the final electrochemical performance. For example, at certain Ni contents, these composite nanofibers display excellent electrochemical performance, such as high reversible capacities, good capacity retention, and excellent rate performance, when directly used as binder-free anodes for rechargeable lithium-ion batteries. However, when the Ni content …

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Microfabrication Of Conductive Polymer Nanocomposite For Sensor Applications, Chaoxuan Liu Jan 2012

Microfabrication Of Conductive Polymer Nanocomposite For Sensor Applications, Chaoxuan Liu

LSU Doctoral Dissertations

This dissertation developed novel microfabrication techniques of conductive polymer nanocomposite and utilized this material as a functional element for various physical sensor applications. Microstructures of nanocomposite were realized through novel microcontact printing and laser ablation assisted micropatterning processes. Prototype devices including large-strain strain sensor and highly-sensitive pressure sensor were demonstrated showing distinct advantages over existing technologies. The polymer nanocomposite used in this work comprised elastomer poly(dimexylsiloxane) (PDMS) as polymer matrix and multi-walled carbon nananotubes (MWCNTs) as a conductive nanofiller. To achieve uniform distribution of carbon nanotubes within the polymer, an optimized dispersion process was developed, featuring a strong organic solvent—chloroform, …

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A Thermodynamic Framework For The Modeling And Optimization Of Crystallization Processes, David John Widenski Jan 2012

A Thermodynamic Framework For The Modeling And Optimization Of Crystallization Processes, David John Widenski

LSU Doctoral Dissertations

Crystallization is a widely used chemical engineering separation unit operation process. Since this technique can produce high purity products it is used for the industrial production of many chemical compounds, such as pharmaceuticals, agrochemicals, and fine chemicals. The production of these products is a multi-million dollar industry. Any methods to improve the production of these products would be highly valued. Thus, the main objective of this work is to target model-based optimal strategies for crystallization operations specifically targeting crystal size and crystal size distribution (CSD). In particular, take the knowledge gained and translate it into an economically and practically feasible …

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