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Title: The design, development, fabrication and testing of a 100 watt skutterudite thermoelectric generator
Creator: Lyle, Matthew
Date: 2011
Collection: Electronic Theses & Dissertations
Description: Thermoelectric technology is a method of renewable, alternative energy that utilizes the Seebeck effect to convert some of the thermal energy in a temperature gradient to electricity. The optimal temperature range for skutterudite thermoelectric devices is around 650°C, making them ideal for high temperature applications. At this temperature range, the skutterudite thermoelectrics have a device-level conversion efficiency of about 9%. As these devices are still in the development stage,...
Show moreThermoelectric technology is a method of renewable, alternative energy that utilizes the Seebeck effect to convert some of the thermal energy in a temperature gradient to electricity. The optimal temperature range for skutterudite thermoelectric devices is around 650°C, making them ideal for high temperature applications. At this temperature range, the skutterudite thermoelectrics have a device-level conversion efficiency of about 9%. As these devices are still in the development stage, testing that simulates real-world conditions is necessary to assess the feasibility of implementing skutterudite thermoelectric technology with current processes. A standardized procedure to test the skutterudite thermoelectric devices has been established to reduce variability in device fabrication and generator assembly. This procedure includes a measurement and tracking system to aid in establishing relationships between component properties and thermoelectric performance. In addition, a technology has been developed to electrically bypass any failed devices to preserve overall power generation.Results indicate that additional efforts are needed to address the high level of thermal stresses the devices experience during operation. Several methods to reduce thermal stresses and investigate potential stressors are proposed. In addition, the successful performance of the electrical bypass technology suggests that it is indeed a viable method of bypassing individual devices for experimental tests. Additional testing and improvements can be made as necessary to implement this technology in the envisioned 1 kW skutterudite thermoelectric generator.
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Title: Rater effects in ITA testing : ESL teachers' versus American undergraduates' judgments of accentedness, comprehensibility, and oral proficiency
Creator: Hsieh, Ching-Ni
Date: 2011
Collection: Electronic Theses & Dissertations
Description: Second language (L2) oral performance assessment always involves raters' subjective judgments and is thus subject to rater variability. The variability due to rater characteristics has important consequential impacts on decision-making processes, particularly in high-stakes testing situations (Bachman, Lynch, & Mason, 1995; A. Brown, 1995; Engelhard & Myford, 2003; Lumley & McNamara, 1995; McNamara, 1996). The purposes of this dissertation study were twofold. First, I wanted to examine rater...
Show moreSecond language (L2) oral performance assessment always involves raters' subjective judgments and is thus subject to rater variability. The variability due to rater characteristics has important consequential impacts on decision-making processes, particularly in high-stakes testing situations (Bachman, Lynch, & Mason, 1995; A. Brown, 1995; Engelhard & Myford, 2003; Lumley & McNamara, 1995; McNamara, 1996). The purposes of this dissertation study were twofold. First, I wanted to examine rater severity effects across two groups of raters, English-as-a-Second-Language (ESL) teachers and American undergraduate students, when raters evaluated international teaching assistants' (ITAs) oral proficiency, accentedness, and comprehensibility. Second, I wanted to identify and compare rater orientations, that is, factors that drew raters' attention when judging the examinees' oral performances. I employed both quantitative and qualitative methodologies to address these issues concerning rater effects and rater orientations in the performance testing of ITAs at a large Midwestern university. Thirteen ESL teachers and 32 American undergraduate students participated in this study. They evaluated 28 potential ITAs' oral responses to the Speaking Proficiency English Assessment Kit (SPEAK). Raters evaluated the examinees' oral proficiency, accentedness, and comprehensibility, using three separate holistic rating scales. Raters also provided concurrent written comments regarding their rating criteria and participated in one-on-one interviews that explored raters' rating orientations. I employed a many-facet Rasch measurement analysis to examine and compare rater severity across rater groups using the computer program FACETS. I compared the written comments across groups to identify major rating criteria employed by the ESL teachers and the undergraduates. I analyzed the interview data to explore the reasons for rating discrepancies across groups. Results of the study suggested that the ESL teachers and the undergraduate raters did not differ in severity with respect to their ratings of oral proficiency. However, the comparisons of ratings in accentedness and comprehensibility were both statistically significant. The undergraduate raters were harsher than the teacher raters in their evaluations of examinees' accentedness and comprehensibility. Additionally, the analysis of the written comments identified six major rating criteria: linguistic resources, phonology, fluency, content, global assessment, and nonlinguistic factors. Cross-group comparisons of the rating criteria indicated that the undergraduate raters tended to evaluate the examinees' oral performances more globally than the ESL teachers did. In contrast, the ESL teachers tended to use a wider variety of rating criteria and commented more frequently on specific linguistic features. The interview protocols revealed that raters' experience with accented speech, perceptions of accent as an important rating criterion, and approaches to rating (i.e. analytical or global), had important bearings on raters' judgments of ITA speech.
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Title: Predicting differential item functioning in cross-lingual testing : the case of a high stakes test in the Kyrgyz Republic
Creator: Drummond, Todd W.
Date: 2011
Collection: Electronic Theses & Dissertations
Description: Cross-lingual tests are assessment instruments created in one language and adapted for use with another language group. Practitioners and researchers use cross-lingual tests for various descriptive, analytical and selection purposes both in comparative studies across nations and within countries marked by linguistic diversity (Hambleton, 2005). Due to cultural, contextual, psychological and linguistic differences between diverse populations, adapting test items for use across groups is a...
Show moreCross-lingual tests are assessment instruments created in one language and adapted for use with another language group. Practitioners and researchers use cross-lingual tests for various descriptive, analytical and selection purposes both in comparative studies across nations and within countries marked by linguistic diversity (Hambleton, 2005). Due to cultural, contextual, psychological and linguistic differences between diverse populations, adapting test items for use across groups is a challenging endeavor. Of paramount importance in the test adaptation process is the proven ability of test developers to adapt test items across groups in meaningful ways. One way investigators seek to understand the level of item equivalence on a cross-lingual assessment is to analyze items for differential item functioning, or DIF. DIF is present when examinees from different language groups do not have the same probability of responding correctly to a given item, after controlling for examinee ability (Camilli & Shephard, 1994). In order to detect and minimize DIF, test developers employ both statistical methods and substantive (judgmental) reviews of cross-lingual items. In the Kyrgyz Republic, item developers rely on substantive review of items by bi-lingual professionals. In situations where statistical DIF detection methods are not typically utilized, the accuracy of such professionals in discerning differences in content, meaning and difficulty between items is especially important. In this study, the accuracy of bi-linguals' predictions about whether differences between Kyrgyz and Russian language test items would lead to DIF was evaluated. The items came from a cross-lingual university scholarship test in the Kyrgyz Republic. Evaluators' predictions were compared to a statistical test of "no difference" in response patterns by group using the logistic regression (LR) DIF detection method (Swaminathan & Rogers, 1990). A small number of test items were estimated to have "practical statistical DIF." There was a modest, positive correlation between evaluators' predictions and statistical DIF levels. However, with the exception of one item type, sentence completion, evaluators were unable to predict which language group was favored by differences on a consistent basis. Plausible explanations for this finding as well as ways to improve the accuracy of substantive review are offered. Data was also collected to determine the primary sources of DIF in order to inform the test development and adaptation process in the republic. Most of the causes of DIF were attributed to highly contextual (within item) sources of difference related to overt adaptation problems. However, inherent language differences were also noted: Syntax issues with the sentence completion items made the adaptation of this item type from Russian into Kyrgyz problematic. Statistical and substantive data indicated that the reading comprehension items were less problematic to adapt than analogy and sentence completion items. I analyze these findings and interpret their implications to key stakeholders, provide recommendations for how to improve the process of adapting items from Russian into Kyrgyz and highlight cautions to interpreting the data collected in this study.
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Title: Curative and rainfastness characteristics of insecticides used to control Spotted Wing Drosophila (Matsumura) in tart cherry productions
Creator: Andika, Ignatius Putra
Date: 2018
Collection: Electronic Theses & Dissertations
Description: Spotted wing drosophila (Drosophila suzukii Matsumura) (SWD) is an invasive pest originated from East Asia, which has caused devastating damaged to soft-skinned fruit productions globally and an increase of growers’ reliance on insecticide to meet market standards. However, the intensive use of insecticides raises community concerns regarding environmental health, human health, and the risk of SWD population to grow resistances. Therefore, exploring other activity modes of insecticides...
Show moreSpotted wing drosophila (Drosophila suzukii Matsumura) (SWD) is an invasive pest originated from East Asia, which has caused devastating damaged to soft-skinned fruit productions globally and an increase of growers’ reliance on insecticide to meet market standards. However, the intensive use of insecticides raises community concerns regarding environmental health, human health, and the risk of SWD population to grow resistances. Therefore, exploring other activity modes of insecticides registered against SWD besides adulticide action may provide information to refine existing insecticide programs. The data from these experiments provide insight of the curative and rainfastness of insecticides registered against SWD in tart cherry productions. The residue data in these experiments compliment the biological data and provide better understanding on how these insecticides work against SWD.
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Title: QTL mapping of post-processing color retention and other traits in two black bean populations
Creator: Bornowski, Nolan M.
Date: 2018
Collection: Electronic Theses & Dissertations
Description: "When black beans are processed for consumption, they can lose their dark coloration due to the leaching of water-soluble pigments called anthocyanins. After hydrothermal processing, beans are commonly a faded brown color instead of the dark black color typical of the dry seed. The aim of this research was to develop mapping populations with different genetic sources of color retention in order to identify regions of the dry bean genome associated with canning quality traits. To this end, two...
Show more"When black beans are processed for consumption, they can lose their dark coloration due to the leaching of water-soluble pigments called anthocyanins. After hydrothermal processing, beans are commonly a faded brown color instead of the dark black color typical of the dry seed. The aim of this research was to develop mapping populations with different genetic sources of color retention in order to identify regions of the dry bean genome associated with canning quality traits. To this end, two half-sibling black bean recombinant inbred line (RIL) populations segregating for post-processing color retention were developed. These RIL populations were phenotyped for canning quality over two years and genotyped using the BARCBean6k_3 BeadChip. A novel phenotyping method using digital image analysis was shown to outperform current methods of quantitative color measurement. QTL for post-processing color retention were detected on six chromosomes, with QTL on Pv03, Pv08, and Pv11 being the most notable for their co-localization with QTL for quantitative measurements of color. In particular, QTL associated with color retention on Pv11 mapped to a very small physical interval and were consistent across years, populations, and phenotyping methodologies. Color retention QTL on Pv08 and Pv11 are good candidates for development of molecular markers that may be used in marker assisted selection (MAS) or early-generation screening to improve post-processing color retention in black beans."--Page ii.
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Title: Implementation of envelope tracking for RF solid state amplifiers
Creator: Larter, Thomas Leigh
Date: 2015
Collection: Electronic Theses & Dissertations
Description: ABSTRACTIMPLEMENTATION OF ENVELOPE TRACKING FOR RF SOLID STATE AMPLIFIERSBy Thomas Larter The Facility for Rare Isotope Beams (FRIB) is currently in its development stages at Michigan State University. The facility uses a large linear accelerator system to accelerate ionized particles which are then collided with other particles in the hopes of finding rare isotopes of elements. This accelerating action depends on several systems to function, with one of the major systems being...
Show moreABSTRACTIMPLEMENTATION OF ENVELOPE TRACKING FOR RF SOLID STATE AMPLIFIERSBy Thomas Larter The Facility for Rare Isotope Beams (FRIB) is currently in its development stages at Michigan State University. The facility uses a large linear accelerator system to accelerate ionized particles which are then collided with other particles in the hopes of finding rare isotopes of elements. This accelerating action depends on several systems to function, with one of the major systems being superconducting cavity structures. These cavities are driven by high-power RF amplifiers which account for a large portion of the accelerator's power consumption. It is important to maximize the efficiency of these amplifiers in order to keep energy costs for the facility low. One of the ways to increase efficiency is to choose an amplifier topology that is highly efficient. A study was done for FRIB testing the prospect of using amplifiers with the envelope tracking (ET) topology. An amplifier's efficiency relies on its output power and the power supplied to it, which are in turn directly related to the output signal voltage and supply rail voltage. In an ET RF amplifier, the supply voltage is made to closely follow the envelope of the output signal voltage. This tracking action allows the RF amplifier to operate with much improved efficiency at low power levels and nearly constant efficiency at high power levels. The ET tests performed for FRIB attempted to verify the validity of ET efficiency gains for RF amplifiers. These tests included the characterization of an RF amplifier, development and verification of an ET control algorithm, and implementation of an ET test bench using FRIB equipment. These tests should attest to the purported increase in efficiency possible with ET and prove that the power consumption budget for the FRIB will benefit from the use of such amplifiers.
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Title: An investigation of the kinesthetic ability and effects of bimanual coordination in patients with multiple sclerosis
Creator: Lincoln, Faith
Date: 2015
Collection: Electronic Theses & Dissertations
Description: "This study identifies the kinesthetic impairment in the upper limb in MS [Multiple Sclerosis] patients and determines if this performance can be modulated by simultaneious utilization of the contralateral limb."--from abstract.

Title: Grammatical gender agreement in L2 Spanish : the role of syntactic context
Creator: Spino-Seijas, Le Anne L.
Date: 2017
Collection: Electronic Theses & Dissertations
Description: A pervasive question in second language (L2) research is whether L2 learners can acquire parameterized functional features that are not instantiated in their first language (L1). While some researchers have argued for a representational deficit (e.g., Clahsen & Muysken, 1989; Hawkins & Chan, 1997), claiming that L2 learners’ competence is fundamentally deficient, others have argued that learners can indeed acquire features that are not instantiated in their L1 (e.g., Prévost & White, 2000;...
Show moreA pervasive question in second language (L2) research is whether L2 learners can acquire parameterized functional features that are not instantiated in their first language (L1). While some researchers have argued for a representational deficit (e.g., Clahsen & Muysken, 1989; Hawkins & Chan, 1997), claiming that L2 learners’ competence is fundamentally deficient, others have argued that learners can indeed acquire features that are not instantiated in their L1 (e.g., Prévost & White, 2000; Schwartz & Sprouse, 1996), and ascribe any optionality to communication pressure or other external factors. In this dissertation, grammatical gender agreement was used as a test case to determine if L2 Spanish learners (L1 = English) can indeed acquire a parametrized feature not present in their L1. Many researchers that investigate grammatical gender agreement do not have a principled reason for investigating a particular type of agreement (e.g., determiner-noun, noun-adjective). It may be the case, though, that not all types of agreement are equally difficult for L2 learners. In studies that investigate whether L2 learners have a representational deficit for grammatical gender agreement, it is therefore impossible to conclude whether learners truly have a representational deficit, or whether they are performing poorly because of the type of agreement under investigation. Therefore, this dissertation tests grammatical gender agreement in three different syntactic contexts that are commonly used in this type of research: determiner-noun (DET-N), noun-adjective (N-ADJ) and null nominal (N-DROP). These syntactic contexts were hypothesized to differ in difficulty for L2 learners, with DET-N being the easiest and N-DROP the most difficult.Native Spanish speakers and L2 learners read a series of sentences embedded with violations of these three different types of grammatical gender agreement while their eye-movements were recorded with an eye-tracker. Participants’ sensitivity was measured both via reading times and self-reports on a post-reading questionnaire. Linear mixed-effects models indicated that native Spanish speakers were sensitive to all three types of grammatical gender agreement, as evidenced by longer reading times on ungrammatical relative to grammatical areas of interest, but L2 Spanish learners were sensitive only to DET-N agreement, and not N-ADJ and N-DROP agreement. The self-reports paralleled these findings, with L2 learners reporting a higher instance of seeing DET-N agreement violations than N-ADJ and N-DROP violations in the experimental stimuli. These results indicate that the L2 learners likely do not have a representational deficit for grammatical gender agreement, and that the type of grammatical gender agreement under investigation matters, as the syntactic context of the agreement may affect performance. Results are discussed in terms of the types of knowledge L2 learners use during online processing in studies that detect sensitivity to grammatical violations.
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Title: Effect of package configuration on barrier properties and sensory perception of flavor
Creator: Kumar, Pankaj, 1979-
Date: 2007
Collection: Electronic Theses & Dissertations

Title: Development of a novel sausage casing made of chitosan and its performance under traditional sausage manufacturing conditions
Creator: Adzaly, Noor Zainah
Date: 2014
Collection: Electronic Theses & Dissertations
Description: The objective of this study was to develop a novel chitosan-based casing for commercial application. In order to do so, chitosan was mixed with cinnamaldehyde, glycerol and Tween 80 in various ratios, and the resulting films were compared to commercial collagen casings for physical and mechanical properties. The chitosan film exhibited different properties due to the interactions between chitosan, glycerol and cinnamaldehyde as identified by FTIR spectrophotometry. Among the different...
Show moreThe objective of this study was to develop a novel chitosan-based casing for commercial application. In order to do so, chitosan was mixed with cinnamaldehyde, glycerol and Tween 80 in various ratios, and the resulting films were compared to commercial collagen casings for physical and mechanical properties. The chitosan film exhibited different properties due to the interactions between chitosan, glycerol and cinnamaldehyde as identified by FTIR spectrophotometry. Among the different chitosan films, the film containing cinnamaldehyde (2.2%, w/v), glycerol (50%, w/w) and Tween 80 (0.2% w/w) shown the same mechanical properties as the collagen casing, with lower water solubility, superior transparency, and better UV light barrier property. As a next step, the selected film was made into a round shape, stuffed with meat batter and compared to meat-stuffed collagen casings for commercial feasibility of the novel casings under traditional sausage manufacturing conditions. Before and after meat stuffing and cooking, both chitosan or collagen (control) casings were compared for mechanical, barrier and physical properties. The results show that, chitosan casing showed better performance as a barrier to water, oxygen, liquid smoke and UV light compared to the collagen casing. In mechanical and physical properties, chitosan casing had higher tensile strength but lower elongation and tensile energy to break, had better transparency and similar water solubility as the collagen casing. These results show the potential of the chitosan casing as an alternative or better choice than the collagen casing for the manufacture of sausages.
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Title: A method for the validation of computational models using digital image correlation and image decomposition
Creator: Sebastian, Christopher M.
Date: 2011
Collection: Electronic Theses & Dissertations
Description: Recently, there has been a drive to create more efficient designs of vehicles. This has led to the use of new materials and more rigorous optimization of components. As the design envelope is pushed and new materials are explored, it is more important than ever to ensure that designs are based on a model that has been validated. Currently, a typical validation consists of a simple point-to-point comparison. This method assumes that the model has identified the areas of high stress correctly,...
Show moreRecently, there has been a drive to create more efficient designs of vehicles. This has led to the use of new materials and more rigorous optimization of components. As the design envelope is pushed and new materials are explored, it is more important than ever to ensure that designs are based on a model that has been validated. Currently, a typical validation consists of a simple point-to-point comparison. This method assumes that the model has identified the areas of high stress correctly, and leaves the rest of the model un-validated.This thesis proposes a method to validate computational models using image decomposition and digital image correlation.Digital image correlation is capable of producing full-field strain maps with on the order of 105 to 106 data points. The challenge then becomes comparing the massive amounts of experimental and simulation data.Image decomposition provides a way to reduce those data sets to less than 100 moments while preserving the original information. These compressed data sets can be compared more easily than the original data.As a part of the validation process, the DIC system was calibrated according to a recently published draft ISO standard.Finally, two studies are presented which use image decomposition to compare simulation and experimental results.The first involves an aluminum plate with a hole loaded in tension.The second is a composite protective panel which is bolted at one end and loaded compressively.
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Title: Development and characterization of a bio-based antimicrobial multi-layered packaging material containing poly lactic acid, chitosan, and grapefruit seed extract
Creator: Gartner, Hunter
Date: 2014
Collection: Electronic Theses & Dissertations
Description: Blend solutions containing poly(lactic acid) (PLA) and chitosan (CS) were prepared with the addition of methyldiphenyl diisocyanate (MDI) and coated on PLA film. Increasing the concentration of MDI modified the surface tension and enhanced wettability. The increase in MDI also resulted in increased H-bonding from urethane groups formed within PLA/CS to improve adhesion. These findings were used to improve wettability and adhesion between the PLA/CS coating and PLA film to develop a completely...
Show moreBlend solutions containing poly(lactic acid) (PLA) and chitosan (CS) were prepared with the addition of methyldiphenyl diisocyanate (MDI) and coated on PLA film. Increasing the concentration of MDI modified the surface tension and enhanced wettability. The increase in MDI also resulted in increased H-bonding from urethane groups formed within PLA/CS to improve adhesion. These findings were used to improve wettability and adhesion between the PLA/CS coating and PLA film to develop a completely bio-based multi-layer film with antimicrobial capacity. The novel antimicrobial film was prepared by coating CS containing grapefruit seed extract (GSE) on the aforementioned PLA/CS coated PLA film. The effectiveness of the antimicrobial film against Salmonella Typhimurium in tomato juice was investigated. A combined effect between the GSE concentration and temperature on the effectiveness of the antimicrobial films against S. Typhimurium in tomato juice was identified. Incorporating GSE into chitosan coatings did not affect the properties of the films initially but did affect these after exposing the films to tomato juice. The tensile strength and elongation at break of films without GSE significantly decreased (p < 0.05) while these properties did not change for films containing GSE. Adhesion between the CS coating and PLA film was significantly reduced (p < 0.05) after exposing the films to tomato juice. Water vapor and oxygen permeability of the films were not affected by either GSE or tomato juice. CS/GSE coated PLA films have the potential to be an effective bio-based antimicrobial material for food packaging applications.
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Title: Shelf life estimation of USP 10mg Prednisone calibrator tablets in relation to dissolution & new windows-based shelf life computer program
Creator: Yoon, Seungyil
Date: 2000
Collection: Electronic Theses & Dissertations

Title: A fracture mechanics-based approach for modeling delamination of spray-applied fire-resistive materials from steel structures
Creator: Arablouei, Amir
Date: 2015
Collection: Electronic Theses & Dissertations
Description: Steel structures exhibit lower fire-resistance due to high thermal conductivity of steel and rapid deterioration of strength and stiffness properties of steel with temperature. Therefore, steel structures are to be provided with fire insulation to achieve required fire resistance. This is often achieved through spray applied fire resistive materials (SFRM) that are externally applied on steel surface. The main function of SFRM is to delay temperature rise in steel, and thus slow down the...
Show moreSteel structures exhibit lower fire-resistance due to high thermal conductivity of steel and rapid deterioration of strength and stiffness properties of steel with temperature. Therefore, steel structures are to be provided with fire insulation to achieve required fire resistance. This is often achieved through spray applied fire resistive materials (SFRM) that are externally applied on steel surface. The main function of SFRM is to delay temperature rise in steel, and thus slow down the degradation of stiffness and strength properties of steel when exposed to fire. Delamination of fire insulation can occur during service life of the structure due to exposure to harsh environmental conditions or due to poor bond properties at the interface of steel and SFRM. Further, high deformation levels in structural members due to extreme loading conditions such as earthquake, impact or explosion can lead to delamination of fire insulation from steel structures. Fire that can develop as a secondary event following an earthquake, explosion or impact (primary events) can cause significant damage and destruction to the steel structure if SFRM applied on the steel members experience fire insulation loss during primary events. For instance, combined effects of impact or blast and ensuing fire could lead to the progressive collapse of structure as in the case of the terrorist attacks on the World Trade Center buildings (NIST, 2005) and collapse of Piper Alpha platform in North Sea (1988).In this research, an experimental-numerical approach is adopted to investigate delamination of fire insulation from steel structures subjected to static loading and also extreme loading conditions such as seismic, impact and blast loading. The cohesive zone behavior at the interface of SFRM and steel is determined through static fracture tests conducted for three types of SFRM namely, mineral fiber-based, gypsum-based and Portland cement-based SFRM. Subsequently, dynamic impact tests are carried out on beams insulated with above three types of SFRM to assess performance of SFRM under dynamic loading and also to assess the effect of strain rate on cohesive zone properties.A fracture mechanics-based numerical model, that can simulate crack initiation and propagation at the interface of steel and fire insulation, is developed in ANSYS and LS-DYNA for low and high strain rate loading conditions, respectively. The numerical approach is validated against both material and structural level tests. The validated numerical model is subsequently applied to quantify the effect of critical factors governing delamination phenomenon namely, fracture energy, elastic modulus and thickness of SFRM. Results from parametric studies under static loading were utilized to identify the critical factors governing delamination of fire insulation from steel structures. Further, these results formed the basis for defining a delamination characteristic parameter that incorporates material-related governing factors in a single parameter and maintains interdependency between them. Results obtained from parametric study under impact loading is also utilized to estimate the dynamic increase factor (DIF) on fracture energy at the interface of steel and SFRM. Eventually, the delamination characteristic parameter is modified to capture differences in the nature of seismic and blast loading conditions, i.e. the way the stresses are transferred to the interface of steel and SFRM.
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Title: Learning paradigms for the identification of elastic properties of composites using ultrasonic guided waves
Creator: Gopalakrishnan, Karthik
Date: 2020
Collection: Electronic Theses & Dissertations
Description: Identification of elastic properties of composites is relevant for both nondestructive materials characterization as well as for in-situ condition monitoring to assess and predict any possible material degradation. Learning paradigms have been well explored when it comes to detection and characterization of defects in safety-critical structures, but are relatively unexplored when it comes to structural materials characterization. In this thesis we propose a learning paradigm that includes the...
Show moreIdentification of elastic properties of composites is relevant for both nondestructive materials characterization as well as for in-situ condition monitoring to assess and predict any possible material degradation. Learning paradigms have been well explored when it comes to detection and characterization of defects in safety-critical structures, but are relatively unexplored when it comes to structural materials characterization. In this thesis we propose a learning paradigm that includes the potential use of Machine Learning (ML) and Deep Learning (DL) algorithms to solve the inverse problem of material properties identification using ultrasonic guided waves. The propagation of guided waves in a composite laminate is modelled using two different modelling techniques as part of the forward problem. Here, we use the two fundamental modes of guided waves, i.e. the anti-symmetric (A0) and the symmetric modes (S0) as features for the proposed learning models. As part of the inverse problem, different learning models are used to map feature space to target space that consists of the material properties of composites. The performance of the algorithms is evaluated based on different metrics and it is seen that the networks are able to learn the mapping and generalize well to unseen examples even in the presence of noise at various levels. Overall, we are able to develop a complete framework consisting of many interlinking data processing algorithms that can effectively estimate and predict the material properties of any given composite.
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Title: Sustainable building materials and systems
Creator: Bharadwaj, Harsha
Date: 2016
Collection: Electronic Theses & Dissertations
Description: "The supply line of a contingency base constitutes its greatest vulnerability. The reliance of a base on supply line can be reduced through maximum use of locally available construction materials and resources. The objective of this work is to make efficient use of indigenous materials should still provide adequate force protection, safety under relevant loads, quality of life, sustainability, energy-efficiency, economy and durability. Seismic, blast, impact and wind resistance are among the...
Show more"The supply line of a contingency base constitutes its greatest vulnerability. The reliance of a base on supply line can be reduced through maximum use of locally available construction materials and resources. The objective of this work is to make efficient use of indigenous materials should still provide adequate force protection, safety under relevant loads, quality of life, sustainability, energy-efficiency, economy and durability. Seismic, blast, impact and wind resistance are among the considerations in development of these building systems. A sandwich composite is devised as the primary module for development of the building system. The indigenous reinforcement systems selected for use in ferrocement sheets were two jute burlaps with different yarn spacing, and chicken mesh. These fabrics were characterized through performance of tension tests. Their failure modes and tensile load-deflection behavior were investigated. The tensile strength, stiffness and ductility of jute burlaps were found to compare favorably with those of chicken mesh, which is a viable reinforcement for use in ferrocement. The flexure and compression test specimens were 1,200 mm long, 300 mm wide and 100 mm thick. The sandwich composite thickness comprised an 80 mm thick indigenous aerated concrete core and two 10 mm thick indigenous ferrocement skins with jute fabric reinforcement. The in-plane shear (diagonal compression) test components were 500 mm square with thickness and cross-sectional designs similar to those of flexure and compression test specimens."--Page ii.
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Title: Error analysis of reflection-only material characterization methods
Creator: Fenner, Raenita Ann
Date: 2011
Collection: Electronic Theses & Dissertations
Description: Material characterization is the process of determining the electrical properties of a material by using knowledge of how electromagnetic waves reflect and transmit through a material sample. This characterization can be critical to the design of high-speed circuits and packaging, microwave remote sensing, bioengineering, food engineering, agriculture, and general materials science. An interesting problem within material characterization is the non-contact, non-destructive characterization of...
Show moreMaterial characterization is the process of determining the electrical properties of a material by using knowledge of how electromagnetic waves reflect and transmit through a material sample. This characterization can be critical to the design of high-speed circuits and packaging, microwave remote sensing, bioengineering, food engineering, agriculture, and general materials science. An interesting problem within material characterization is the non-contact, non-destructive characterization of conductor-backed media. Conductor-backed media are materials which are directly adhered to a good or a perfect electric conductor (PEC). This scenario occurs in real-life applications such as the characterization of in-situ materials or characterization of shielding apparatus. For this specific case, reflection-only methods must be used because measurement of transmission properties is impossible due to the PEC backing.The main focus of this dissertation is the study of the strengths and weaknesses of various reflection-only material characterization methods by performing a thorough error analysis. More specifically, the propagation of measurement errors into extracted material parameters is investigated. Such analysis is lacking in the material characterization area. Key contributions of this research are (1) a general formulation for deriving reflection-only material characterization methods, (2) a general process for determining the propagated error into many reflection-only material characterization methods, (3) a method for characterizing conductor-backed media, (4) expanding the use of interval analysis in the electromagnetic community, and (5) determining the impact of wave curvature on free-space reflection-only material characterization methods.
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Title: Experimental and numerical studies on venous ulcers
Creator: Zagorski, Wu Pan
Date: 2017
Collection: Electronic Theses & Dissertations
Description: Venous ulcers are the most common and severe skin wounds occurring in lower legs. They are painful, hard to heal and have a 78% chance of recurrence after two years, which leads to frequent visits to wound care clinics and results in huge financial burdens to the patients, family, and society. Contemporary treatments include compression stockings, drugs, and surgeries. However, these only treat the ulcers after they have occurred. Therefore, it is necessary to understand the pathology of...
Show moreVenous ulcers are the most common and severe skin wounds occurring in lower legs. They are painful, hard to heal and have a 78% chance of recurrence after two years, which leads to frequent visits to wound care clinics and results in huge financial burdens to the patients, family, and society. Contemporary treatments include compression stockings, drugs, and surgeries. However, these only treat the ulcers after they have occurred. Therefore, it is necessary to understand the pathology of ulcer formation, which will then allow us to predict the onset of an ulcer and implement preventive measures early. The commonly accepted theory of venous ulcer pathology is that the ulcers are caused by chronic venous insufficiency (CVI) which is a resultant of calf muscle pump failure. CVI causes blood pooling in the lower leg, leads to inflammation, skin edema, tissue necrosis, and ultimately skin ulcers. However, various hypotheses existed between the stages of blood pooling and the ulceration. Therefore, the goals of this research were to: i) determine the blood flow response to loading in lower legs between venous ulcers patients and a healthy population; ii) quantify the hemodynamic parameters that contribute to the differences in blood flow; iii) understand the progressive changes between inflammation and skin edema in the development of skin ulcers. To address the first goal, a blood perfusion test was performed on the lower legs of ulcer patients and a healthy group. External normal, and combined normal and shear loads were applied to the lower legs. The blood perfusion profiles were analyzed and results showed that the ulcerated legs were significantly different than healthy legs in response to load and reactive hyperemia. The legs that did not have open wounds but were from the same ulcer patient exhibited an intermediate trend between the wounded and healthy legs. This suggests a progressive change existed during ulcer development. The second goal was achieved by the development of a Windkessel based circuit model. The model output was compared with the blood flow profiles from the perfusion tests. Patient-specific parameters were obtained and compared across the wounded, non-wounded, and healthy legs. Results indicated that significant differences existed in localized vessel resistance and compliance between wounded and healthy legs, suggesting a threshold of those parameters existed from each category. The results explained the differences in locally measured blood perfusion and indicated the potential of identifying populations at risk of developing venous ulcers. Finally, the third goal was reached by the development of a skin Finite Element (FE) model with series of parametric studies. The influence of the glycosaminoglycans (GAGs) and sodium during inflammation on the skin edema and tissue damage were explored. Results showed that the increased GAGs and sodium content led to edema and an increased fluid pressure within the tissue. This explained the increased reactive hyperemia from wounded legs in the perfusion tests. Increased fluid pressure causes tissue ischemia and an increased tissue stress; both have been shown to cause tissue damage and wound formation. The FE model provides insights to the detailed pathological events that happen between inflammation, edema and skin ulceration.
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Title: Towards automated model revision for fault-tolerant systems
Creator: Abujarad, Fuad
Date: 2010
Collection: Electronic Theses & Dissertations

Title: The ability of English speakers to respond to the structural cues of written language : measuring instruments
Creator: Hepler, Hal Weigel
Date: 1966
Collection: Electronic Theses & Dissertations

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