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Finite Element (FE) analysis is a powerful numerical technique widely utilized to simulate the real-world response of complex engineering structures. With the advancements in adaptive optimization frameworks, multi-fidelity (coupled shell-solid) FE models are increasingly sought during the early design stages where a large design space is being explored. This is because multi-fidelity models have the potential to provide accurate solutions at a much lower computational cost. However, the time and effort required to create accurate and optimal multi-fidelity models with acceptable meshes for highly complex structures is still significant and is a major bottleneck in the FE modeling process. Additionally, there is a significant level of subjectivity involved in the decision-making about the multi-fidelity element topology due to a high dependence on the analyst's experience and expertise, which often leads to disagreements between analysts regarding the optimal modeling approach and heavy losses due to schedule delays. Moreover, this analyst-to-analyst variability can also result in significantly different final engineering designs. Thus, there is a greater need to accelerate the FE modeling process by automating the development of robust and adaptable multi-fidelity models as well as eliminating the subjectivity and art involved in the development of multi-fidelity models. This dissertation presents techniques and frameworks for accelerating the finite element modeling process of multi-fidelity models. A framework for the automated development of multi-fidelity models with adaptable 2-D/3-D topology using the parameterized full-fidelity and structural fidelity models is presented. Additionally, issues related to the automated meshing of highly complex assemblies is discussed and a strategic volume decomposition technique blueprint is proposed for achieving robust hexahedral meshes in complicated assembly models. A comparison of the full-solid, full-shell, and different multi-fidelity models of a highly complex stiffened thin-walled pressure vessel under external and internal tank pressure is presented. Results reveal that automation of multi-fidelity model generation in an integrated fashion including the geometry creation, meshing and post-processing can result in considerable reduction in cost and efforts. Secondly, the issue of analyst-to-analyst variability is addressed using a Decision Tree (DT) based Fuzzy Inference System (FIS) for recommending optimal 2D-3D element topology for a multi-fidelity model. Specifically, the FIS takes the structural geometry and desired accuracy as inputs (for a range of load cases) and infers the optimal 2D-3D topology distribution. Once developed, the FIS can provide real-time optimal choices along with interpretability that provides confidence to the analyst regarding the modeling choices. The proposed techniques and frameworks can be generalized to more complex problems including non-linear finite element models and as well as adaptable mesh generation schemes. / Doctor of Philosophy / Structural analysis is the process of determining the response (mainly, deformation and stresses) of a structure under specified loads and external conditions. This is often performed using computational modeling of the structure to approximate its response in real-life conditions. The Finite Element Method (FEM) is a powerful and widely used numerical technique utilized in engineering applications to evaluate the physical performance of structures in several engineering disciplines, including aerospace and ocean engineering. As optimum designs are increasing sought in industries, the need to develop computationally efficient models becomes necessary to explore a large design space. As such, optimal multi-fidelity models are preferred that utilize higher fidelity computational domain in the critical areas and a lower fidelity domain in less critical areas to provide an optimal trade-off between accuracy and efficiency. However, the development of such optimal models involves a high level of expertise in making a-priori and a-posteriori optimal modeling decisions. Such experience based variability between analysts is often a major cause of schedule delays and considerable differences in final engineering designs. A combination of automated model development and optimization along with an expert system that relieves the analyst of the need for experience and expertise in making software and theoretical assumptions for the model can result in a powerful and cost-effective computational modeling process that accelerates technological advancements. This dissertation proposes techniques for automating robust development of complex multi-fidelity models. Along with these techniques, a data-driven expert system framework is proposed that makes optimal multi-fidelity modeling choices based on the structural configuration and desired accuracy level.

Edamame is becoming more popular in the U.S. due to its high nutritional value and potential health benefits. However, more than 70% of edamame is imported from outside of the U.S. Therefore, developing elite edamame genotypes is critically desirable to increase the domestic production of edamame in the U.S. Genotype, planting location, and harvest time play essential roles in the chemical composition of edamame, which further decide edamame's nutritional value and sensory characteristics. Therefore, the first goal of this study is to comprehensively evaluate the chemical composition of edamame genotypes grown in different locations. Ten selected edamame genotypes were grown in three locations in the U.S. - Whitethorne, Virginia (VA), Little Rock, Arkansas (AR) and Painter, VA. Sugars, alanine, protein, oil, neutral detergent fiber (NDF), starch, ash, and moisture contents, were comprehensively analyzed. The results showed that location had significant effects on all chemical components of edamame with p < 0.05. Compared to Painter and Little Rock, genotypes planted in Whitethorne had higher averaged free sucrose, fructose, glucose, raffinose, stachyose, and starch contents and total sweetness. The highest crude protein and oil contents were found on edamame planted in Painter, while Little Rock produced edamame with the highest free alanine, ash, and moisture contents. Genotype significantly affected chemical compositions except for NDF and raffinose. Therefore, planting location and edamame genotype should be considered when producing elite edamame for the U.S. market. Chemical composition changes with the development of edamame; therefore, harvest time is essential for harvesting high-quality edamame. The second objective of this study is to quantify the changes in both physical and chemical properties of edamame over bean development and apply a combined spectroscopy and machine learning (ML) technique to help determine the optimal harvest time. Physical and chemical properties were analyzed for edamame harvested at R5 (beginning seed), R6 (full seed), and R7 (beginning maturity) growth stages, and the spectral reflectance (360 – 740 nm) of edamame pods was measured using a handheld spectrophotometer. The samples harvested at different stages were labeled as 'early,' 'ready,' and 'late.' At R6, pod/bean weight and pod thickness reached the peak and then stayed stable, while sugar, alanine, starch, and glycine also peaked at R6 but declined afterward. The spectra-based ML method had high accuracy (0.95) when classifying 'early' and 'late' edamame, and the accuracy was 0.87 for classifying 'early' and 'ready' edamame. These results indicated that this spectra-based ML method could determine the optimal harvest time of edamame. Food waste and loss not only lead to economic loss but also significant greenhouse gas emissions. With edamame food/snack production increasing, edamame shells, the low-value byproduct from this processing, will potentially threaten the environment. Similar to other food processing byproducts, edamame shell is rich in dietary fiber (DF). However, the high concentration of insoluble dietary fiber (IDF) limits its application as a food additive. Therefore, extraction/modification processes are needed to convert IDF to soluble dietary fiber (SDF) and improve the properties of edamame shell-derived DF. Ball milling is one of the most efficient techniques to break down biomaterials into sub-micro-level particles. Citric acid, as a natural and safe food additive, can help break down cell walls and improve the dissolution of SDF by ionizing the hydrogen ions with carboxyl groups. Therefore, the third objective of this study is to develop a process that combines ball milling and citric acid treatments to produce SDF from edamame shells. We investigated different treatment parameters, including different citric acid concentrations, treatment temperatures and time, and the application of ball milling. To determine if the combined treatment can potentially improve the properties of the produced SDFs, we characterized the physicochemical, morphological, structural, rheological, thermal, and functional properties of SDFs produced at different conditions. The results showed that the highest SDF yield (19.5%) was found when the edamame shells were pretreated by a ball mill. In addition, the combined citric acid and ball milling treatment altered several properties of the produced SDFs, including particle size, morphology, and crystallinity. Moreover, ball milling treatment led to a higher exothermic temperature peak of SDF indicating better thermal stability. All produced SDFs significantly elevated the production of short-chain fatty acids during in vitro fermentation (compared to the control fermentation) which indicated their potential benefits of promoting gut health. Overall, we demonstrated that ball-milling-assisted citric acid processing can be an effective green technique to produce SDF from edamame shells. The SDF produced from edamame shells can be regarded as a promising and novel ingredient with great potential to be used in foods. / Doctor of Philosophy / Edamame is becoming increasingly popular among consumers in the U.S. because it is nutritious and good for health. However, more than 70% of edamame in the U.S. market is imported from other countries. Therefore, having more edamame genotypes that adapt to the growing environment in the U.S. will help increase the domestic production of edamame. Genotype and planting location are essential in deciding edamame's nutritional value and taste. Therefore, the first objective of this study is to comprehensively understand the nutritional value of different edamame genotypes grown in three planting locations. The results showed that both location and genotype affected the nutritional values of edamame, indicating that planting location and edamame genotype should be considered when developing better edamame for the U.S. market. Nutritional value and sweetness change with the growth of edamame beans. Therefore, harvest time is crucial for harvesting edamame with better nutrition and taste. This study's second objective is to observe edamame's nutritional factors and sweetness over bean development and develop a method using a handheld colorimeter to help determine the optimal harvest time. The results showed that the edamame harvested at the full seed stage (called R6) is the sweetest compared to the other two stages. In addition, the handheld colorimeter combined with the machine learning technique showed high accuracy in separating 'early' and 'late' harvested edamame and 'early' and 'ready' harvested samples. These results indicated that the combination of colorimeter and machine learning could help determine the optimal harvest time of edamame. Food waste and loss not only lead to economic loss but also significant greenhouse gas emissions. Edamame shells, the low-value byproduct from edamame snack/food processing, will potentially threaten the environment if edamame consumption keeps increasing. Like other food waste, edamame shell is rich in dietary fiber (DF). Therefore, it is vital to find a way to recover the DF in edamame for other applications. Ball milling is a green technology that can efficiently break down big particles. Citric acid is a natural and safe food additive and can help break down insoluble cell walls. Therefore, this study aims to produce soluble dietary fiber (SDF) from edamame shells using ball milling and citric acid. We proved that ball-milling assisted acid processing can be an environmentally friendly method to produce edamame shell SDF which can potentially be used as a suitable food ingredient.

A high-order hybrid discontinuous Galerkin finite element method (DG-FEM) is developed for multi-layered curved panels having large deformation and finite strain. The kinematics of the multi-layered shells is presented at first. The Jacobian matrix and its determinant are also calculated. The weak form of the DG-FEM is next presented. In this case, the discontinuous basis functions can be employed for the displacement basis functions. The implementation details of the nonlinear FEM are next presented. Then, the Consistent Orthogonal Basis Function Space is developed. Given the boundary conditions and structure configurations, there will be a unique basis function space, such that the mass matrix is an accurate diagonal matrix. Moreover, the Consistent Orthogonal Basis Functions are very similar to mode shape functions. Based on the DG-FEM, three dedicated finite elements are developed for the multi-layered pipes, curved stiffeners and multi-layered stiffened hydrofoils. The kinematics of these three structures are presented. The smooth configuration is also obtained, which is very important for the buckling analysis with large deformation and finite strain. Finally, five problems are solved, including sandwich plates, 2-D multi-layered pipes, 3-D multi-layered pipes, stiffened plates and stiffened multi-layered hydrofoils. Material and geometric nonlinearities are both considered. The results are verified by other papers' results or ANSYS. / Master of Science

No / The potential of Mg in Arctica islandica as a climate proxy is explored through analysis of live-collected shells from Irvine Bay, NW Scotland. Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) analysis of the right hand valve from two specimens indicates that seasonal Mg/Ca variations do not correlate with seawater temperature. The highest Mg/Ca typically occurs at the annual growth checks in ~ November¿February. Mg/Ca variations between growth checks are significant in one specimen but usually not significant in the other. Mg/Ca measurements taken laterally across the band (i.e. perpendicular to direction of the growth) to determine heterogeneity of the aragonite deposited at the same time indicates that Mg/Ca concentration decreases with increasing distance from the periostracum in both shells. X-ray Absorption Near Edge Spectroscopy (XANES) indicates that Mg is not substituted into aragonite but is hosted by a disordered phase e.g. organic components or nanoparticles of an inorganic phase. Shell Mg/Ca variations may reflect changes in the concentration or composition of the disorded phase, as well as changes in the composition of the extrapallial fluid used for calcification. Such changes could reflect the relative transportation rates of Mg and Ca to the calcification site.

Yes / Shell beads appear to have been one of the earliest examples of personal adornments. Marine shells identified far from the shore evidence long-distance transport and imply networks of exchange and negotiation. However, worked beads lose taxonomic clues to identification, and this may be compounded by taphonomic alteration. Consequently, the significance of this key early artefact may be underestimated. We report the use of bulk amino acid composition of the stable intra-crystalline proteins preserved in shell biominerals and the application of pattern recognition methods to a large dataset (777 samples) to demonstrate that taxonomic identification can be achieved at genus level. Amino acid analyses are fast (<2 hours per sample) and micro-destructive (sample size <2 mg). Their integration with non-destructive techniques provides a valuable and affordable tool, which can be used by archaeologists and museum curators to gain insight into early exploitation of natural resources by humans. Here we combine amino acid analyses, macro- and microstructural observations (by light microscopy and scanning electron microscopy) and Raman spectroscopy to try to identify the raw material used for beads discovered at the Early Bronze Age site of Great Cornard (UK). Our results show that at least two shell taxa were used and we hypothesise that these were sourced locally.

L'émergence des logiciels de modélisation a récemment conduit à une complexification des formes architecturales. Les processus de prise de forme sont maintenant pleinement intégrés dans l'univers numérique et il est désormais possible de décrire précisément des géométries aux multiples courbes à l'aide de l'ordinateur. Toutefois, lorsque des techniques traditionnelles sont employées pour construire de telles géométries, il en résulte une utilisation importante de ressources et un décuplement du temps de chantier. Dans ce contexte, les résilles en bois se présentent comme une solution crédible pour répondre à la matérialisation des formes issues des explorations numériques. En abordant les concepts de forme, structure, matière et lumière sous l'angle de l'architecture biophilique, cette recherche-création traite de l'intégration entre les bâtiments et leur environnement en abordant la génération de la forme architecturale. Plus spécifiquement, elle présente une classification de précédents de résilles en fonction de leur complexité et propose d'investiguer des treillis hybrides pour faciliter leur mise en place. Elle développe également une méthode constructive alliant des grilles souples aux membrures de petites sections combinées à un réseau primaire de composantes rigides. De plus, la recherche s'intéresse aux ambiances des résilles et suggère que la lumière puisse être un intégrateur de l'architecture biophilique. Enfin, la thèse avance que les résilles en bois devraient se démocratiser davantage, autant pour la réalisation de bâtiments singuliers que génériques. / The emergence of modelling software has recently led to the complexification of architectural forms. Form-finding processes are now fully integrated into the digital world and it is now possible to accurately describe geometries with multiple curves using computers. However, when traditional techniques are used to construct such geometries, it results in a significant use of resources and an increase in construction time. In this context, timber gridshells present themselves as a credible solution to the materialization of shapes resulting from digital explorations. By approaching the concepts of form, structure, matter and light from the perspective of biophilic architecture, this research-creation deals with the integration between buildings and their environment. More specifically, it presents a classification of gridshells according to their complexity and proposes to investigate hybrid structures to facilitate their implementation. It develops a constructive method combining flexible grids with small section members combined with a primary network of rigid components. Moreover, the research evaluates the ambiences of gridshells and suggests that light can be an integrator of biophilic architecture. In short, the thesis argues that timber gridshell should become more democratic, both for the creation of singular and generic buildings.

Die vorliegende Arbeit hat die Entwicklung und Validierung eines Analysealgorithmus zur objektiven Auswertung der Materialverteilung entlang der Zarge an gezogenen Karton-formziehteilen zum Ziel. Die dafür verwendeten Messdaten werden durch Oberflächenab-tastung mit konfokaler Sensorik erzeugt. Unter Anwendung des Analysealgorithmus wer-den die Einflüsse der Prozessparameter auf die Materialverteilung ermittelt. Abschließend wird aus den gewonnenen Daten ein Ansatz zur Berechnung der Werkzeuggeometrie ent-wickelt. Zur Bestimmung der Materialverteilung wird die Zarge beidseitig abgetastet. Aus der Diffe-renz der Radien von Außen- und Innenkontur wird der Dickenverlauf entlang der Zarge bestimmt, die die Materialverteilung beschreibt. Die Messung mit konfokalen Sensoren wird mit mikroskopischen Aufnahmen von Mikrotomschnitten und röntgentomographi-schen Aufnahmen geprüft. Der Mittelwert und die Standardabweichung des Dickenverlaufs charakterisieren die Mate-rialverteilung. Der Analysealgorithmus ermittelt aus den durch Sensoren aufgenommenen Daten die charakteristischen Werte. In der Auswertung zeigt sich, dass eine Höhere Zieh-stempeltemperatur als Ziehbüchsentemperatur sowie eine hohe Temperatursumme die mittlere Dicke verringern. Eine hohe Faltenhalterkraft und eine hohe Stempeltemperatur bewirken eine gleichmäßigere Materialverteilung. Der ermittelte Zusammenhang von der Beeinflussung des Mittelwertes der Dicke mit den Temperaturunterschieden von Stempel und Büchse wird durch ein Modell der thermischen Ausdehnung von Stempel und Büchse belegt. / The present thesis comprises the development and validation of an algorithm for the objec-tive evaluation of data on material distribution alongside the architrave of drawn cardboard shells. The necessary data are obtained through detection of the surface with confocal sensors. The influences of the process parameters on material distribution are investigated with algorithm. Resulting from this data, the basis for the calculation of the tools geometry is developed. The determination of material distribution is accomplished by double-sided optical scanning of the architraves inner and outer surface. The trend of cardboard thickness alongside the architrave is calculated by the subtracion of the inside radius from the outside radius of the cardboard shell. The cardboard thickness describes material distribution. The measures with confocal sensors are approved of examined microtome cuts under microscope and x-ray analyses. Material distribution is characterised by average of the thickness and standard deviation of thickness. The analysis algorithm calculates with sensor data the characteristic values. A higher temprature of the drawing die as the temprature of the drawing box and the sum of temperatures lead to a decrease of the average thickness. The combination of a high die temperature and a high force applied by the blankholder result in a more even material distribution. The identified correlation of average thickness and temperature gradients between the drawing die and the box is discribed by thermal expansion of die and box.

M. Tech. (Department of Chemistry, Faculty of Applied and Computer Science), Vaal University of Technology / Cadmium and cobalt complexes of urea and thiourea were synthesized using ethanol as a solvent. All complexes were refluxed at 70 - 80 °C, left to cool at room temperature, washed with methanol and acetone to remove impurities and dried at an open environment. The characterization of complexes was done using FTIR spectroscopy, elemental analysis and TGA. The complexes were found to coordination with the ligands through sulphur and oxygen atoms to the metal, instead of nitrogen. These were as results of wavelength shifting from high to low frequency from spectra of the complexes as compare to their free ligands. These observations make these complexes good candidates for the possible use in synthesis of metal sulphides or oxides nanoparticles. Thermogravimetric analyses of all the complexes were conducted to check the stability of use as precursors for nanoparticles at low and high temperature. A number of thiourea and urea complexes with cadmium and cobalt have been prepared and used in the preparation of metal sulphides/oxides nanoparticles. Complexes start to decompose at low temperature about 100°C and the last decomposition step was at about 800-900°C, which is convenient to thermal decomposition of precursors in the high boiling solvents or capping agent to prepare surface capped metal sulphides/oxides nanoparticles. The complexes were easy to synthesize, low cost and stable in air and were obtained in reasonable yields. All the complexes reported in this study have been used as single source molecular precursor in the preparation of cadmium oxide, cadmium sulphide, cobalt oxide, cobalt sulphide nanoparticles (normal) and as mixture of any two complexes to form core-shells nanoparticles. Quality nanoparticles synthesis requires three components: precursors, organic surfactants and solvents. The synthesis of the nanoparticles can be thought of as a nucleation event, followed by a subsequent growth period. Both the nucleation and growth rates were found to be dependent upon factors such as temperature, growth time, and precursor concentration. For a continuous flow system the residence time (at nucleation and growth conditions) was also found to be important. In order to separate the nucleation and growth events, injection techniques were employed to achieve rapid nucleation of nanoparticles with final size dictated by the growth temperature and/or residence time through the growth zone of the reaction system. Good crystalline normal nanoparticles were obtained from thermolysis of the precursors in hexadecylamine (HDA) as the capping agent at fixed concentrations, temperature and time. All nanoparticles showed a blue-shift in band edges with good photoluminescence behaviour which is red-shifted from their respective band edges and XRD patterns, the crystal structure are in hexagonal phase. The particles showed rods, spheres and hexagonal shapes. Nucleation and growth mechanism brings new avenue in nanostructures called core-shells, which have been reported to have improved luminescence, quantum yields, decreased fluorescence lifetimes, and benefits related to the tailoring of the relative band-gap positions between the two materials. In this study cadmium and cobalt complexes of urea and thiourea were separately dispersed in TOP and injected separately (allowing nucleation/core to occur, followed by the shell) in hot HDA at 180ºC for 1hour to yield core-shell nanoparticles. Parameters, such as concentration, temperature and capping molecule as factor affecting nucleation and growth of the core-shells were monitored. The core-shell nanoparticles were characterized by UV/Vis spectroscopy, XRD and TEM. We observed spherical, tripod, bipods, hexagonal and irregular shaped nanoparticle as the concentration of the precursors was increasing, however we were able to form core-shells nanoparticles in one set of experiment 1:3 CdS-CdO, which are assumed to be a reverse type I coreshells nanoparticles. Exciton absorption peaks at higher energy than the fundamental absorption edge of bulk indicate quantum confinement effect in nanoparticles as a consequence of their small size. XRD patterns, crystals range from hexagonal, cubic and mixture of hexagonal and orthorhombic. A low temperature studies were also conducted a mixture of hexagonal and sphererical shapes with sheets like onion morphology were observed. / NRF HUB & SPOKES (VUT)

[pt] Nesta tese, as vibrações não-lineares e a estabilidade de uma casca cilíndrica contendo um fluido são estudadas com base em modelos de dimensão reduzida, isto é, modelos com um número reduzido de graus de liberdade. A partir dos funcionais de energia potencial e cinética de uma casca cilíndrica, deduzem-se suas equações de movimento. O campo de deformações da casca cilíndrica segue a teoria não- linear de Donnell para cascas abatidas. O fluido é considerado interno à casca irrotacional, não-viscoso e incompressível, sendo descrito a partir de um potencial de velocidade que leva em consideração a interação entre o fluido e a estrutura. Para resolver o sistema de equações de equilíbrio da casca, desenvolve-se um procedimento analítico que permite obter os campos de deslocamento axial e circunferencial em função dos deslocamentos laterais, além de atender as condições de contorno do problema. Desta forma, reduz-se o sistema de equações de equilíbrio a uma única equação diferencial parcial que é resolvida com o método de Galerkin. A determinação dos deslocamentos laterais é feita a partir de técnicas de perturbação que ordena os modos não-lineares de acordo com sua importância na solução da casca cilíndrica. Comprova-se essa ordenação através do método de Karhunen-Loève que fornece, também, uma expansão ótima para os deslocamentos laterais. Além dessas técnicas, apresenta-se uma redução polinomial que relacionam as amplitudes dos modos não-lineares com a amplitude do modo linear, criando uma expansão modal com 1 GDL. Apresentam-se respostas no tempo, fronteiras de instabilidade e diagramas de bifurcação para uma casca cilíndrica submetida a dois tipos de carregamentos harmônicos, pressão lateral e carga axial. A seguir, são propostos alguns critérios para a análise da a integridade do sistema dinâmico tanto para um sistema com 1 GDL quanto para um sistema multidimensional através da evolução e erosão das bacias de atração. Por fim, estuda-se o comportamento de cascas cilíndricas parcialmente cheias, mostrando a influência da altura do fluido nas fronteiras de instabilidade e curvas de ressonância da casca cilíndrica. / [en] The nonlinear vibrations and stability of a fluid-filled cylindrical shell is investigated using reduced order models. First, the nonlinear equations of motion of the cylindrical shell are deduced based on the expressions for the potential and kinetic energy, which are obtained using Donnell shallow shell theory. The internal fluid is considered to be irrotational, non- viscous and incompressible. It is described by a velocity potential that takes into account the fluid-shell interaction. A procedure is proposed to obtain analytically the axial and circumferential displacements of the shell, satisfying the in-plane equations of motion and the associated boundary conditions. So, the problem is reduced to one partial differential equation of motion which is solved by the Galerkin method. The transversal displacement field is obtained by perturbation techniques. This enables one to identify the relevance of each term in the nonlinear expansion of the vibration modes. Then, the Karhunen-Loève method is employed to investigate de relative importance of each mode obtained by the perturbation analysis on the nonlinear response and to deduce optimal interpolation function to be used in the Galerkin procedure. A SDOF model is also obtained by relating the modal amplitudes of the nonlinear modes to the vibration amplitude of the linear mode. Time responses, instability boundaries and ifurcation diagrams are obtained for cylindrical shells subjected to harmonic lateral and axial loads. Different procedures for the analysis of the shell integrity are proposed based on the evolution and erosion of the basins of attraction in state-space. Finally, the influence of the fluid height on the stability boundaries and resonance curves is studied.