The preliminary goal of this study is to determine the effects of processing conditions, compositions and microstructural morphologies of the constituents on the physical and thermo-mechanical properties of alumina (Al_2O_3) reinforced aluminum (Al) composites. Composites with 0, 5, 10, 20 and 25 vol% Al_2O_3 were manufactured using powder metallurgy method. The elastic properties (Young's and shear modulus) and the coefficient of thermal expansion (CTE) of the composites were determined using Resonant Ultrasound Spectroscopy (RUS) and Thermo Mechanical Analyzer (TMA) respectively at various temperatures. Increasing compacting pressure improved relative density (or lowered porosity) of the composites. Furthermore, increasing the Al_2O_3 vol% in the composite increased the elastic moduli and reduced the CTE of the composites. Increasing the testing temperature from 25 to 450 oC, significantly reduced the elastic moduli of the composites, while the CTE of the composites changed only slightly with temperatures. Secondly, the goal of this study is to determine the effect of microstructures on the effective thermo-mechanical properties of the manufactured Al-Al_2O_3 composites using finite element (FE) method. Software OOF was used to convert the SEM micrographs of the manufactured composites to FE meshed models, which were then used to determine the effective elastic modulus and CTE. It was observed that, effective modulus dropped by 19.7% when porosity increased by 2.3%; while the effective CTE was mildly affected by the porosity. Additionally, the effect of residual stress on the effective thermo-mechanical properties was studied, and the stress free temperature of the composites was determined. Another objective of this study is to examine the stress-strain response of Al-Al_2O_3 composites due to compressive loads at various temperatures. Elastic modulus, yield stress and strain hardening parameters were determined from the stress-strain curves and their dependency on temperature, porosity and volume fraction were studied. The experimental results were compared with the numerical results. It was observed that high-localized stresses were present near the pores and at the interfaces between Al and Al_2O_3 constituents. Finally, functionally graded materials (FGMs) with varying Al_2O_3 concentration (0, 5and 10 vol%) in Al were manufactured; and their stress-strain response and CTE were determined at various temperatures.

To assess the relationships of body mass index (BMI) on arterial stiffness at rest and post-maximal treadmill graded exercise testing (GXT). Forty-four apparently healthy, young adult males (22.1 ± 0.48 years) were recruited and divided into either a healthy weight (H, ≤24.9 kg/m2), overweight (OV, 24.9-29.9 kg/m2) or obese (OB, ≥29.9 kg/m2) group based on BMI. All subjects underwent arterial stiffness (carotid-femoral pulse wave velocity, cfPWV), blood pressure (BP), pulse pressure (PP), mean arterial pressure (MAP) and body composition (bioelectrical impedance analysis, BIA) measurements at rest. Following the GXT, measures of arterial stiffness (cfPWV) and BP were acquired. Resting measures of cfPWV, BMI, systolic BP, diastolic BP, MAP, and PP were significantly (p <0.05) greater in OV and OB compared with H. Compared with OV, OB had a greater BMI. Relative peak oxygen consumption (VP2peak) was greater in H compared with OV and OB (p<0.05). systolic BP was positively associated, whereas VO2peak was inversely related to cfPWV (p<0.05). No significant inter-group interactions were observed with cfPWV after the GXT. However, interactions were observed for SBP, DBP and PP (p<0.05). In young men with varying BMI, SBP and VO2peak were associated with resting cfPWV. However, similar cardiovascular responses were observed between groups after a maximal GXT.

The focus of this dissertation is on the development of an additive manufacturing system and methodology for fabricating structures with functionally graded porous internal properties and complex three-dimensional external characteristics. For this purpose, a multi-scale three-dimensional printing system was developed, with capabilities and fabrication methodologies refined in the context of, but not limited to, manufacturing of porous bone substitutes. Porous bone implants are functionally graded structures, where internally, the design requires a gradient in porosity and mechanical properties matching the functional transition between cortical and cancellous bone regions. Geometrically, the three-dimensional shape of the design must adhere to the anatomical shape of the bone tissue being replaced. In this work, control over functionally graded porous properties was achieved by integrating specialized modules in a custom-made additive manufacturing system and studying their effect on fabricated constructs. Heterogeneous porous properties were controlled by: (i) using a micro-syringe deposition module capable of embedding sacrificial elements with a controlled feature size within the structure, (ii) controlling the amount of binder dispersed onto the powder substrate using a piezoelectric printhead, (iii) controlling the powder type or size in real-time, and/or (iv) selecting the print layer stacking orientation within the part. Characterization methods included differential scanning calorimetry (DSC)-thermo gravimetric analysis (TGA) to establish the thermal decomposition of sacrificial elements, X-ray diffraction (XRD) and dispersive X-ray spectroscopy (EDAX) to investigate the chemical composition and crystallinity, scanning electron microscopy (SEM) and optical microscopy to investigate the physical and structural properties, uniaxial mechanical loading to establish compressive strength characteristics, and porosity measurements to determine the bulk properties of the material. These studies showed that the developed system was successful in manufacturing embedded interconnected features in the range of 100-500 $ \mu m $, with a significant impact on structural properties resulting in bulk porosities in the range of 30-55% and compressive strength between 2-50 MPa. In this work, control over the the three-dimensional shape of the construct was established iteratively, by using a silhouette extraction image processing technique to determine the appropriate anisotropic compensation factors necessary to offset the effects of shrinkage in complex-shaped parts during thermal annealing. Overall shape deviations in the range of +/- 5-7 % were achieved in the second iteration for a femoral condyle implant in a sheep model. The newly developed multi-scale 3DP system and associated fabrication methodology was concluded to have great potential in manufacturing structures with functionally graded properties and complex shape characteristics.

Functionally graded materials processed by the thermal spray techniques such as electron beam physical vapor deposition and plasma spray forming are known to have an orthotropic structure with reduced mechanical properties. Debonding related failures in these types of material systems occur due to embedded cracks that are perpendicular to the direction of the material property gradation. These cracks are inherently under mixed-mode loading and fracture analysis requires the extraction of the modes I and II stress intensity factors. The present study aims at developing semi-analytical techniques to study embedded crack problems in graded orthotropic media under various boundary conditions. The cracks are assumed to be aligned parallel to one of the principal axes of orthotropy. The problems are formulated using the averaged constants of plane orthotropic elasticity and reduced to two coupled integral equations with Cauchy type dominant singularities. The equations are solved numerically by adopting an expansion - collocation technique. The main results of the analyses are the mixed mode stress intensity factors and the energy release rate as functions of the material nonhomogeneity and orthotropy parameters. The effects of the boundary conditions on the mentioned fracture parameters are also duly discussed.

The objective of this study is to develop crack growth analysis methods for functionally graded materials under mode I cyclic loading by using finite element technique. The study starts with the analysis of test specimens which are given in ASTM standard E399. The material properties of specimens are assumed to be changing along the thickness direction according to a presumed variation function used for the modeling of functionally graded materials. The results of the study reveal the influence of different material variation functions on the crack growth behavior. In the second part, the growth of an elliptical crack which is a common case in engineering applications is analyzed. First, mode I cycling loading is applied perpendicular to the crack plane and crack growth profiles for a certain number of cycles are obtained for homogeneous materials. Then, the code is extended for the analysis functionally graded materials. The material properties are assumed to vary as an exponential function along the major or minor axis direction of the crack. The results can be used to examine the crack profile and material constants&rsquo / influence for a certain number of cyclic loading.

Thesis (Ph. D.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Systems Science and Industrial Engineering, 2009. / Includes bibliographical references.

Submitted by DAYANA CAMPANELLI DE MORAIS null (dayanacampanelli@gmail.com) on 2017-12-22T03:50:36Z No. of bitstreams: 1 para impressão final.pdf: 3931660 bytes, checksum: d52b37974d258d1d9c1647f7cca67f54 (MD5) / Approved for entry into archive by Silvana Alvarez null (silvana@ict.unesp.br) on 2018-01-04T18:53:29Z (GMT) No. of bitstreams: 1 morais_dc_me_sjc.pdf: 3931660 bytes, checksum: d52b37974d258d1d9c1647f7cca67f54 (MD5) / Made available in DSpace on 2018-01-04T18:53:29Z (GMT). No. of bitstreams: 1 morais_dc_me_sjc.pdf: 3931660 bytes, checksum: d52b37974d258d1d9c1647f7cca67f54 (MD5) Previous issue date: 2017-11-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O presente estudo teve como objetivo desenvolver vitrocerâmicas de dissilicato de lítio com gradiente funcional de densidade, inspirado no gradiente natural que existe entre o esmalte e a dentina. Primeiramente o vidro de composição: 33,33% mol de Li2O e 66,67% mol de SiO2 foi obtido pelo método fusão/resfriamento. Em seguida foram preparadas amostras com estruturas homogêneas do vidro a base de dissilicato de lítio para determinação dos melhores parâmetros de sinterização. Três diferentes tratamentos térmicos, determinados com base no resultado da análise diferencial de calorimetria foram utilizados: 850 °C/3h; 900 °C/3h e 950 °C/3h. A caracterização desses materiais foi realizada através da difração de raios X, microscopia eletrônica de varredura, método de Arquimedes e ensaio de flexão biaxial (n=10). O tratamento térmico de 950 oC obteve os melhores resultados, sendo o escolhido para a realização das próximas etapas do estudo. Com a finalidade de otimizar a estética, foi adicionada cerâmica feldspática (VITAVM®9) ao vidro SiO2-Li2O na proporção de 10%, 15% e 20% (n=30). Foi observado que a adição de 10% de VM9 não alterou a resistência do material, e quanto maior a quantidade de VM9, maior foi a translucidez e menor foram o módulo elástico e a densidade. Com isso, foram preparadas vitrocerâmicas bioinspiradas com gradiente funcional de densidade nas seguintes sequências de camadas: uma com 10% de VM9, outra com 15% e a última com 20%. Não houve diferença na resistência à flexão biaxial do grupo com gradiente, quando a camada mais densa estava voltada para o lado de tração, com o grupo com 15% de VM9 com estrutura homogênea. A translucidez do grupo com gradiente foi equivalente ao grupo homogêneo mais translúcido, com 20% de VM9. Concluiu-se que foi possível sintetizar uma vitrocerâmica de dissilicato de lítio funcionalmente graduada, onde uma boa resistência mecânica e uma boa translucidez foram unidas.

Criminology’s most recent theoretical tradition involves examination of the developmental onset, continuity, and desistance from offending behavior across the life course. A prominent life course perspective organized around social bonding was proffered by Robert J. Sampson and John H. Laub in dual volumes that include Crime in the Making: Pathways and Turning Points Through Life (1993), and Shared Beginnings, Divergent Lives (2003). Because Sampson and Laub’s age-graded theory is based on a sample of White males born in the 1920s and 1930s, and matured during a historical period of vast economic growth, the universal theoretical processes emphasized in their theory may be overstated. Such assumptions may not generalize to more heterogeneous samples that includes minorities and individuals that vary in their levels of offending. The present research evaluates the generalizability of the age-graded theory through examination of data collected from a representative and contemporary sample of adolescents followed into adulthood. In addition, this study seeks to examine an alternate turning point from deviant conduct, specifically religiosity/spirituality. Building on prior studies that explore the role of religiosity on change processes across race and ethnicity (Chu & Sung, 2009; Stansfield, 2017), the current investigation addresses open questions relating to the nature of the religion-desistance relationship. Multilevel mixed effects models are utilized to estimate over time the separate impact of religious behavior and religious beliefs on deviant conduct, to further assess a religious turning point effect across subgroups disaggregated by race/ethnicity, and to evaluate the influence of religiosity on change from deviant outcomes characterized as violations of secular and ascetic standards. Analyses of religiosity/spirituality on these differing forms of deviance across race/ethnicity are also conducted. In contrast to the hypothesized relationships, study findings reveal very little evidence of a religious/spiritual turning point effect in enacting change from deviant behaviors in the main models. Similar results indicate that religiosity indicates minimal differences in change from deviant conduct when the sample is disaggregated across race and ethnicity. Findings point to the nuances of the religion-desistance relationship, and depends upon processes that may involve attendance to church services or spiritual beliefs, and may be conditional on the type of deviance outcome examined—whether in violation of a secular or ascetic standard. Along with a discussion of these findings, limitations of the study, directions for future research, and implications for policy are provided.

Alarm calls are one of the essential components of antipredator behaviour in birds. In this study I recorded and analysed alarm responses of the barred warbler (Sylvia nisoria) to different mounts of avian predators and nonpredators. The information about danger is encoded through graded structure in its unspecific alarm call type.

xi, 95 p. : ill. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / We investigate some homological properties of graded algebras. If A is an R -algebra, then E (A) := Ext A ( R, R ) is an R-algebra under the cup product and is called the Yoneda algebra. (In most cases, we assume R is a field.) A well-known and widely-studied condition on E(A) is the Koszul property. We study a class of deformations of Koszul algebras that arises from the study of equivariant cohomology and algebraic groups and show that under certain circumstances these deformations are Poincaré-Birkhoff-Witt deformations. Some of our results involve the [Special characters omitted] property, recently introduced by Cassidy and Shelton, which is a generalization of the Koszul property. While a Koszul algebra must be quadratic, a [Special characters omitted] algebra may have its ideal of relations generated in different degrees. We study the structure of the Yoneda algebra corresponding to a monomial [Special characters omitted.] algebra and provide an example of a monomial [Special characters omitted] algebra whose Yoneda algebra is not also [Special characters omitted]. This example illustrates the difficulty of finding a [Special characters omitted] analogue of the classical theory of Koszul duality. It is well-known that Poincaré-Birkhoff-Witt algebras are Koszul. We find a [Special characters omitted] analogue of this theory. If V is a finite-dimensional vector space with an ordered basis, and A := [Special characters omitted] (V)/I is a connected-graded algebra, we can place a filtration F on A as well as E (A). We show there is a bigraded algebra embedding Λ: gr F E (A) [Special characters omitted] E (gr F A ). If I has a Gröbner basis meeting certain conditions and gr F A is [Special characters omitted], then Λ can be used to show that A is also [Special characters omitted]. This dissertation contains both previously published and co-authored materials. / Committee in charge: Brad Shelton, Chairperson, Mathematics; Victor Ostrik, Member, Mathematics; Christopher Phillips, Member, Mathematics; Sergey Yuzvinsky, Member, Mathematics; Van Kolpin, Outside Member, Economics