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Fatigue Crack Growth Under Residual Stresses Around Holes, Ramesh Nagaralu
Fatigue Crack Growth Under Residual Stresses Around Holes, Ramesh Nagaralu
Theses and Dissertations
Compressive residual stresses induced by tensile overloads, compressive under loads, or by a cold-expansion process in specimens containing a circular hole and their influence on subsequent fatigue crack growth in aluminum alloys are studied. The finite element method is used to calculate residual stresses. The superposition method, which uses crack-tip stress intensity factors for cases involving remote loading and residual stresses, is used to calculate crack growth life for three kinds of tests from the literature: (1) fatigue of a circular hole specimen after an overload or under load, (2) single crack growing from a circular hole after a severe …
Study Of Partial Discharge Activity In Magnet Wires Aged By Combined Stresses, Ashwini Mani
Study Of Partial Discharge Activity In Magnet Wires Aged By Combined Stresses, Ashwini Mani
Theses and Dissertations
Partial discharge testing is a nondestructive method of identifying possible premature insulation breakdown. Magnet wires are used in various electrical equipment like injection coils, solenoids, small transformers and motors. Winding wires used in high voltage systems are subjected to several stresses during operation, which considerably lowers their lifetime. A prolonged combined effect of these stresses causes aging of the wires, inception of partial discharge activity, and degradation of the organic material in the enamel coating and varnish used by the manufacturer. The tests were conducted for AWG 30 and AWG 31 twisted magnet wire samples. The samples are aged under …
Two- And Three-Plane Job Risk Classification Using Motion Capture: An Examination Of The Marras Et Al. Model, 1993, Tara Marie Cappelli
Two- And Three-Plane Job Risk Classification Using Motion Capture: An Examination Of The Marras Et Al. Model, 1993, Tara Marie Cappelli
Theses and Dissertations
Lower Back Disorders account for 16-19% of work related claims and 33-41% of dollars paid in workers? compensation (as cited in Marras, 1999), with impacts to society approaching $100 billion dollars annually (as cited in Marras et al., 1999). Dr. William Marras engineered a device to track trunk kinematics in order to develop a Job Risk Classification Model for predicting high-risk group probability of lower back injury. The device has been validated, but other technologies such as 3-D motion capture can potentially gather the same data. This study examined the use of motion capture to apply two- and three-plane lifting …
Cyanate Ester, Epoxy And Epoxy/Cyanate Ester Matrix Polyhedral Oligomeric Silsesquioxane Nanocomposites, Kaiwen Liang
Cyanate Ester, Epoxy And Epoxy/Cyanate Ester Matrix Polyhedral Oligomeric Silsesquioxane Nanocomposites, Kaiwen Liang
Theses and Dissertations
Cyanate ester (PT-15, Lonza Corp) composites containing the inorganic-organic hybrid polyhedral oligomeric silsesquioxanes (POSS), octaaminophenyl(T8)POSS (C6H4NH2)8(SiO1.5)8, cyanopropylheptacyclopentyl(T8)POSS, (C5H9)7(SiO1.5)8(CH2) 3CN or TriSilanolPhenylPOSS (C42H38O12Si7), were synthesized respectively. These PT-15/POSS composites were characterized by FT-IR, X-ray diffraction (XRD), small-angle neutron scattering (SANS), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (X-EDS), transmission electron microscopy (TEM), dynamic mechanical thermal analysis (DMTA) and three-point bending flexural tests. XRD, TEM and IR data are all consistent with molecular dispersion of octaaminophenyl(T8)POSS and TriSilanolPhenylPOSS due to the chemical bonding of the POSS macromer into the continuous cyanate ester network phase. In contrast to octaaminophenyl(T8) POSS and TriSilanolPhenylPOSS, …
Solubility Studies On The Naalob2s-Nanob3s-Hb2so System, Mi-Hee Jung
Solubility Studies On The Naalob2s-Nanob3s-Hb2so System, Mi-Hee Jung
Theses and Dissertations
An investigation of the sodium aluminate-sodium nitrate system was conducted. The effect of sodium nitrate on the solubility of aluminum is important to the retrieval of waste from the tanks at the Hanford nuclear facility located in the state of Washington. Experiments were performed on the NaAlO2 - NaNO3 - H2O system at 25?aC and 50?aC. The results obtained from these experiments were then compared to predictions from the Environmental Simulation Program (ESP, OLI Systems, Inc.) and available literature data. The presence of sodium nitrate increased the solubility of sodium aluminate in water. Sodium nitrate exhibited a greater effect on …
Investigating Traditional Instruction And Problem-Based Learning At The Elementary Level, Ann Wiley Scott
Investigating Traditional Instruction And Problem-Based Learning At The Elementary Level, Ann Wiley Scott
Theses and Dissertations
The purpose of this study was to determine if Problem-Based Learning (PBL) is as effective an instructional method at the elementary level as traditional instruction in learning content. This study also is a contribution to the literature on PBL in the elementary classroom. The research design was quasi-experimental with a non-equivalent control group. A pilot study was conducted in science classes prior to the commencement of the research project in social studies. Eighty-eight students participated in the two studies. The control groups received instruction in a traditional format, and the experimental groups received instruction through the use of PBL. The …
Critical Properties Of Small World Ising Models, Xingjun Zhang
Critical Properties Of Small World Ising Models, Xingjun Zhang
Theses and Dissertations
In this dissertation, the critical scaling behavior of magnetic Ising models with long range interactions is studied. These long range interactions, when imposed in addition to interactions on a regular lattice, lead to small-world graphs. By using large-scale Monte Carlo simulations, together with finite-size scaling, the critical behavior of a number of different models is obtained. The Ising models studied in this dissertation include the z-model introduced by Scalettar, standard small-world bonds superimposed on a square lattice, and physical small-world bonds superimposed on a square lattice. From the scaling results of the Binder 4th order cumulant, the order parameter, and …
Parallel Compositing Of Multi-Temporal Satellite Imagery Using Temporal Map Algebra, Bijay Shrestha
Parallel Compositing Of Multi-Temporal Satellite Imagery Using Temporal Map Algebra, Bijay Shrestha
Theses and Dissertations
Spatio-temporal satellite image analysis is a technique for monitoring spatial and temporal changes of land cover and oceanic locations on earth. Temporal Map Algebra (TMA) is a novel technique developed by Jeremy Mennis and Roland Viger for analyzing a time series of satellite imagery using simple algebraic operators that treats time series of imagery as a threedimensional data set, where two dimensions encode planimetric position on earth surface and the third dimension encodes time. The high dimensionality of raster data leads to high computational cost, which is why parallel computation is attractive. This thesis describes the design, implementation, andmperformance evaluation …
Automatic Cad Model Processing For Downstream Applications, Paresh S. Patel
Automatic Cad Model Processing For Downstream Applications, Paresh S. Patel
Theses and Dissertations
Computer Aided Design (CAD) models often need to be processed due to data translation issues and requirements of the downstream applications like computational field simulation, rapid rototyping, computer graphics,computational manufacturing, and real-time rendering before they can be used. Automatic CAD model processing tools can significantly reduce the amount of time and cost associated with the manual processing.In this dissertaion, automated topology generation and feature removal techniques are developed to prepare suitable models with mimunum user interaction. A topology generation algorithm, commonly known as CAD repairing/healing, is presented to detect commonly found geometrical and topological issues like cracks, gaps, overlaps, intersections, …
A Micro-Cooling, Heating, And Power (M-Chp) Instructional Module, Jason Ryan Oliver
A Micro-Cooling, Heating, And Power (M-Chp) Instructional Module, Jason Ryan Oliver
Theses and Dissertations
Cooling, Heating, and Power (CHP) is an emerging category of energy systems consisting of power generation equipment coupled with thermally activated components. The application of CHP systems to residential and small commercial buildings is known as micro-CHP (m-CHP). This instructional module has been developed to introduce engineering students to m-CHP. In the typical engineering curriculum, a number of courses could contain topics related to m-CHP. Thermodynamics, heat transfer, HVAC, heat and power, thermal systems design, and alternate energy systems courses are appropriate m-CHP topics. The types of material and level of analysis for this range of courses vary. In thermodynamics …
Fast Reconfiguration Algorithm Development For Shipboard Power Systems, Yan Huang
Fast Reconfiguration Algorithm Development For Shipboard Power Systems, Yan Huang
Theses and Dissertations
Todays protection schemes for shipboard applications, such as the zone-based differential protection, are efficient, fast, and reliable for fault detection. However, these protection schemes do not consider the system stability or power balance problems that occur with fault isolation and the system reconfiguration. This thesis focuses on developing the extended protection function including the fast reconfiguration function that intends to maintain the power balance of the unfaulted subsystem. Graph theory is utilized to represent the shipboard power system topology in matrices, and matrix operations are developed to represent the corresponding power system topology change and evaluate the outcome of the …
Online Professional Development: The Experiences Of A First-Time Facilitator, Renee Gammill
Online Professional Development: The Experiences Of A First-Time Facilitator, Renee Gammill
Theses and Dissertations
Donmoyer (1990) suggested that knowledge gained from our own experiences or that of others may be applied to the improvement of practice. The purpose of this study was to provide insight into the experiences of a first-time online facilitator. The research question for this study was: How does a first-time facilitator understand the process of delivering instruction in an online environment? A case study design was applied to this research. The researcher/participant was the case under study in the context of the delivery of online instruction. The researcher who was also the online instructional facilitator experienced the process of delivering …
Evaluation Of Chitosan Gelatin Complex Scaffolds For Articular Cartilage Tissue Engineering, Harshal Prabhakar Mahajan
Evaluation Of Chitosan Gelatin Complex Scaffolds For Articular Cartilage Tissue Engineering, Harshal Prabhakar Mahajan
Theses and Dissertations
In search of better scaffolding materials for in vitro culture of chondrocytes, the combination of chitosan (similar to glycosoaminoglycans) and gelatin (denatured collagen) was tested due to its resemblance to cartilage extra-cellular matrix (ECM). Porous scaffolds were fabricated from chitosan gelatin blends (1:1, 2:1, and 3:1). The response of chondrocytes to them was evaluated from the amount of sulphated GAG and collagen type 2 secreted after 3 and 5 weeks. The effect due to static (transwell inserts) and dynamic (rotating bioreactor) culture methods was analyzed. Results indicate that 1:1 chitosan gelatin blends showed the best chondro-conductive potential. The rotating bioreactor …
Finite Element Simulations Of Three-Dimensional Microstructurally Small Fatigue Crack Growth In 7075 Aluminum Alloy Using Crystal Plasticity Theory, Stephen R (Stephen Riley) Johnston
Finite Element Simulations Of Three-Dimensional Microstructurally Small Fatigue Crack Growth In 7075 Aluminum Alloy Using Crystal Plasticity Theory, Stephen R (Stephen Riley) Johnston
Theses and Dissertations
This thesis discusses plasticity-induced crack closure based finite element simulations of small fatigue cracks in three dimensions utilizing crystal plasticity theory. Previously, modeling has been performed in two dimensions using a double-slip crystal plasticity material model. The goal of this work is to extend that research using a full three-dimensional FCC crystal plasticity material model implementation that accounts for all twelve FCC slip systems. Discussions of Python scripts that were written to perform analyses with the commercial finite element code ABAQUS are given. A detailed description of the modeling methodology is presented along with results for single crystals and bicrystals. …
Design Optimization Of A Parallel Hybrid Powertrain Using Derivative-Free Algorithms, Sachin Kumar Porandla
Design Optimization Of A Parallel Hybrid Powertrain Using Derivative-Free Algorithms, Sachin Kumar Porandla
Theses and Dissertations
A Hybrid Electric Vehicle (HEV) is a complex electro-mechanical-chemical system that involves two or more energy sources. The inherent advantages of HEVs are their increased fuel economy, reduced harmful emissions and better vehicle performance. The extent of improvement in fuel economy and vehicle performance greatly depends on selecting optimal component sizes. The complex interaction between the various components makes it difficult to size specific components manually or analytically. So, simulation-based multi-variable design optimization is a possible solution for such kind of system level design problems. The multi-modal, noisy and discontinuous nature of the Hybrid Vehicle design requires the use of …
Plasma Steroid And Vitellogenin Concentrations, Activity Of Cathepsins, And Egg Protein Content During Oocyte Maturation, And Influence Of Hormone Injection In Four Commercial Strains Of Channel Catfish Ictalurus Punctatus, Marinela Barrero-Monzon
Plasma Steroid And Vitellogenin Concentrations, Activity Of Cathepsins, And Egg Protein Content During Oocyte Maturation, And Influence Of Hormone Injection In Four Commercial Strains Of Channel Catfish Ictalurus Punctatus, Marinela Barrero-Monzon
Theses and Dissertations
Profiles of plasma estradiol and testosterone concentrations, cathepsin D, L, and B activities, and quantitative and qualitative protein content were developed and evaluated in four commercial strains of channel catfish, Gold Kist (2), Thompson and NWAC-103 for one year (age 2 to age 3). Great variation between individuals of the same strain precluded the identification of any significant, strain-specific differences for the variables under investigation. When variables from fish of all strains were collectively evaluated over time, both estradiol and testosterone concentrations significantly increased in July and then later from February to April. The increase in hormone concentration was accompanied …
Empirical Findings On Persuasiveness Of Recommender Systems For Customer Decision Support In Electronic Commerce, Qinyu Liao
Theses and Dissertations
More and more companies are making online presence by opening online stores and providing customers with company and products information but the overwhelming amount of information also creates information overload for the customers. Customers feel frustrated when given too many choices while companies face the problem of turning browsers into actual buyers. Online recommender systems have been adopted to facilitate customer product search and provide personalized recommendation in the market place. The study will compare the persuasiveness of different online recommender systems and the factors influencing customer preferences. Review of the literature does show that online recommender systems provide customers …
Individualistic Roamers Or Community Builders?:Differences And Boundaries Among Rvers, Gloria Anne Mattingly
Individualistic Roamers Or Community Builders?:Differences And Boundaries Among Rvers, Gloria Anne Mattingly
Theses and Dissertations
The number of leisure and working RVers roaming America?s highways, now conservatively estimated at over eight million, continues to increase (Curtin 2001; Sommer 2003). In spite of their growing presence and unique lifestyle, these populations remain sociologically understudied. This exploratory case study of two distinctly different RV parks is a small but significant step toward filling that research gap. At both RV parks I found a diverse population of individualists who value self-contained travel, freedom, relaxation, and sociality. In spite of sharing a collective, subcultural lifestyle, they differed along multiple axes. Marked differences separate RVers into three broad groups (full-timers, …
Mechanical Testing And Evaluation Of Epoxy Resins At Cryogenic Temperatures, Justin Reed Jackson
Mechanical Testing And Evaluation Of Epoxy Resins At Cryogenic Temperatures, Justin Reed Jackson
Theses and Dissertations
The objective of this research is to develop a test methodology to be used in determining which material properties affect the ultimate performance of a composite overwrapped pressure vessel (COPV) at liquid nitrogen (LN2) temperatures. The test methodology being evaluated is based on that used for ambient performance of COPVs and includes: resin properties, resin/fiber interface and COPV burst data. The suitability of these tests at LN2 temperatures will be evaluated. The resin properties are investigated by use of tensile tests to determine: strain to failure (%å), failure stress (óys), and elastic modulus (E). TThe objective of this research is …
Testing The Floristic Quality Assessment Index In Natural And Created Wetlands In Mississippi, Usa, Brook Danielle Herman
Testing The Floristic Quality Assessment Index In Natural And Created Wetlands In Mississippi, Usa, Brook Danielle Herman
Theses and Dissertations
The U.S. Environmental Protection Agency has mandated that states must include the use of biological assessments in their water quality laws to assess the biological integrity of aquatic systems. The Floristic Quality Assessment Index (FQAI), which uses wetland vegetation to assess the biological integrity of an ecosystem, has not been tested in Mississippi. The purpose of this study was to test the efficiency of the FQAI in wetlands along a gradient of human influence. Coefficients of conservatism (CC) were assigned to plant species based on their tolerance to disturbance and fidelity to habitat. A negative correlation was found between the …
Reliability And Validity Of Virtual Build Methodology For Ergonomics Analyses, Tinghao Wu
Reliability And Validity Of Virtual Build Methodology For Ergonomics Analyses, Tinghao Wu
Theses and Dissertations
This study was conducted to assess the validity and reliability of the Virtual Build methodology for ergonomics design and analysis. Thirty-six human subjects participated in this study and performed a set of six tasks. The tasks were performed twice in both real and virtual environment. The subject?s motion in performing tasks was analyzed by ergonomics assessments by using Virtual Build methodology. Criteria-related validity was evaluated by comparing the Virtual Build ergonomic assessment results with manual calculation. Test-retest reliability was evaluated by correlating ergonomics assessment results between two trials. The result shows that the Virtual Build methodology is reliable for ergonomic …
Screening Soybean Genotypes For High Temperature Tolerance By In Vitro Pollen Germination, Pollen Tube Length And Physiological Techniques, Mohammed A. Salem
Screening Soybean Genotypes For High Temperature Tolerance By In Vitro Pollen Germination, Pollen Tube Length And Physiological Techniques, Mohammed A. Salem
Theses and Dissertations
We are now witnessing changing environmental conditions and these changes will likely continue into the coming decades due to projected increases in temperatures on the earth surface. Recent model projections suggest that the global mean surface air temperatures will increase by 1.4 to 5.8 °C by 2100. The consequences of these high temperatures include reductions in crop yields. Soybean is one of the major crops grown in the US, where high temperatures (>35 °C) during reproductive growth decreased yield. Two experiments were conducted to determine the effects of temperature on soybean pollen germination properties and identify responses to temperature …
The Use Of Compression Precracking Constant Amplitude (Cpca) Test Method To Obtain Near-Threshold Fatigue Crack Growth Behavior In Aa7075-T7351, Dustin Henry Mcknight
The Use Of Compression Precracking Constant Amplitude (Cpca) Test Method To Obtain Near-Threshold Fatigue Crack Growth Behavior In Aa7075-T7351, Dustin Henry Mcknight
Theses and Dissertations
Traditionally, pre-cracking has been performed under tension-tension loading, followed by a load reduction scheme to obtain fatigue crack growth rate data in the near threshold regime. These data have been shown to exhibit load history effects due to remote crack closure. An alternative test method has been developed to minimize these load history effects. This test procedure uses compression pre-cracking to initiate a crack, followed by constant amplitude loading to grow the crack to failure. Compression-compression (C-C) loading as a means of forming a starter crack for fatigue crack growth is a relatively new concept. Cracks grown under C-C loading …
Work Replication: A Communication Optimization For Loci, Krunal Navinchandra Soni
Work Replication: A Communication Optimization For Loci, Krunal Navinchandra Soni
Theses and Dissertations
For distributed memory architectures, communication cost is a significant source of overhead in parallel scientific applications. Many proposed communication optimizations duplicate the behavior of well-written hand-tuned parallel code. Because of continuous changes in architectural components, these types of low-level optimizations are not always effective. This thesis seeks to develop a high-level optimization of work replication in which computations are replicated to minimize communications. There exist performance trade-offs between computation cost and communication cost because of work replication. Due to these trade-offs, it is required to determine which computations should be replicated to improve overall performance. This research presents the development …
An Adaptive Wireless Lan Mac Scheme To Achieve Maximum Throughput And Service Differentiation, Wei Zha
An Adaptive Wireless Lan Mac Scheme To Achieve Maximum Throughput And Service Differentiation, Wei Zha
Theses and Dissertations
With the explosive deployment of wireless LAN technology in the past few years and increasing demand on multimedia applications, the efficient utilization of the precious wireless radio link resources and support of Quality of Service (QoS) in WLANs has become a prominent research issue. In this thesis, an adaptive p-persistent based I 802.11 MAC scheme in WLANs has been proposed. The proposed scheme can maximize the total channel throughput, and also provide service differentiation among multiple traffic classes. This is achieved by updating the transmission probabilities for the stations that compete for transmissions in a WLAN, adaptively based on the …
The Geology And Hydrology Of The Proposed Upper Mccurtain Creek Watershed Impoundment Choctaw County, Mississippi, Leonard D (Leonard Dwight) Rawlings
The Geology And Hydrology Of The Proposed Upper Mccurtain Creek Watershed Impoundment Choctaw County, Mississippi, Leonard D (Leonard Dwight) Rawlings
Theses and Dissertations
The McCurtain Creek watershed was proposed for a large reservoir project resulting in the commissioning of this study to assess the site?s geology, hydrogeology, and surface hydrology to find whether or not the site was suitable. Data was collected from 57 geophysical logs from coal exploration boreholes to produce geologic and aquifer cross sections. A program to assess discharge identified surface hydrology characteristics of the stream at five locations. Twenty-seven geotechnical boreholes, 23 standpipe piezometers, and the data from the coal exploration were used to map the water table using ArcGIS 8.3 software. Eighteen piezometers at stream sites, used to …
Mechanical And Physical Properties Of Preservative-Treated Strandboard, John Warren Kirkpatrick
Mechanical And Physical Properties Of Preservative-Treated Strandboard, John Warren Kirkpatrick
Theses and Dissertations
The purpose of this research was to quantify properties of strandboard panels manufactured with various preservatives at loading levels effective against native termites. Panels were manufactured using nine different formulations. The method of preservative addition was also examined for some preservative formulations, increasing the total number of preservative treatments to twelve. Panels were manufactured with one target retention for each preservative treatment. An effective preservative loading relative to termites was established by previous studies or referencing current standards. Mechanical testing performed included static bending and internal bond. Physical testing included water absorption, thickness swell, and linear expansion. Few treatments met …
Combining Static Analysis And Dynamic Learning To Build Context Sensitive Models Of Program Behavior, Zhen Liu
Combining Static Analysis And Dynamic Learning To Build Context Sensitive Models Of Program Behavior, Zhen Liu
Theses and Dissertations
This dissertation describes a family of models of program behavior, the Hybrid Push Down Automata (HPDA) that can be acquired using a combination of static analysis and dynamic learning in order to take advantage of the strengths of both. Static analysis is used to acquire a base model of all behavior defined in the binary source code. Dynamic learning from audit data is used to supplement the base model to provide a model that exactly follows the definition in the executable but that includes legal behavior determined at runtime. Our model is similar to the VPStatic model proposed by Feng, …
Exploring Extensions Of Traditional Honeypot Systems And Testing The Impact On Attack Profiling, Robert Wesley Mcgrew
Exploring Extensions Of Traditional Honeypot Systems And Testing The Impact On Attack Profiling, Robert Wesley Mcgrew
Theses and Dissertations
This thesis explores possibilities for extending the features of honeypot systems to decrease the chance of an attacker discovering that they have compromised a honeypot. It is proposed that by extending the period of time that an attacker spends on a honeypot oblivious to its status, more information relevant to profiling the attacker can be gained. Honeypots are computer systems that are deployed in a way that attackers can easily compromise them. These systems, which contain no production data, are useful both as early warning systems for attacks on production systems, and for studying the tools, techniques, and motives of …
Evaluation Of Hatchery And Growout Factors For The Successful Production And Stocking Of Juvenile Gulf Coast Walleye, Justin L. Wilkens
Evaluation Of Hatchery And Growout Factors For The Successful Production And Stocking Of Juvenile Gulf Coast Walleye, Justin L. Wilkens
Theses and Dissertations
Temperature-dependent weight gain of Gulf coast and northern strain walleye Sander vitreus fingerlings was determined by rearing fish in flow-through aquaria at different water temperatures (range 15-32°C). Maximum growth of Gulf coast and northern strain walleye occurred between 20 and 26°C, and weight gain of northern walleye exceeded that of the Gulf coast strain by 1.5 times. An acclimated chronic exposure method to assess upper thermal limits determined that walleye survived 35, 9, and 1 days at 33, 34, and 35°C, respectively. A post pond-rearing feed-training practice (21 d) at a mean density of 6,290 ± 1,247 fish/m3 using formulated …