Design space exploration (DSE) is used to improve and understand engineering designs. Such designs must meet objectives and structural requirements. Design improvement is non-trivial and requires new DSE methods. Turbomachinery manufacturers must continue to improve existing engines to keep up with global demand. Two challenges of turbomachinery DSE are: the time required to evaluate designs, and knowing which designs to evaluate. This research addressed these challenges by developing novel surrogate and principal component analysis (PCA) based DSE methods. Node and PCA-based surrogates were created to allow faster DSE of turbomachinery blades. The surrogates provided static stress estimation within 10% error. Surrogate error was related to the number of sampled finite element (FE) models used to train the surrogate and the variables used to change the designs. Surrogates were able to provide structural evaluations three to five orders of magnitude faster than FEA evaluations. The PCA-based surrogates were then used to create a PCA-based design workflow to help designers know which designs to evaluate. The workflow used either two-point correlation or stress and geometry coupling to relate the design variables to principal component (PC) scores. These scores were projections of the FE models onto the PCs obtained from PCA. Analysis showed that this workflow could be used in DSE to better explore and improve designs. The surrogate methods were then applied to vibratory stress. A computationally simplified analysis workflow was developed to allow for enough fluid and structural analyses to create a surrogate model. The simplified analysis workflow introduced 10% error but decreased the computational cost by 90%. The surrogate methods could not directly be applied to emulation of vibration due to the large spikes which occur near resonance. A novel, indirect emulation method was developed to better estimate vibratory responses Surrogates were used to estimate the inputs to calculate the vibratory responses. During DSE these estimations were used to calculate the vibratory responses. This method reduced the error between the surrogate and FEA from 85% to 17%. Lastly, a PCA-based multi-fidelity surrogate method was developed. This assumed the PCs of the high and low-fidelities were similar. The high-fidelity FE models had tens of thousands of nodes and the low-fidelity FE models had a few hundred nodes. The computational cost to create the surrogate was decreased by 75% for the same errors. For the same computational cost, the error was reduced by 50%. Together, the methods developed in this research were shown to decrease the cost of evaluating the structural responses of turbomachinery blade designs. They also provided a method to help the designer understand which designs to explore. This research paves the way for better, and more thoroughly understood turbomachinery blade designs.

abstract: Biodiversity is required to guarantee proper ecosystem structure and function. However, increasing anthropogenic threats are causing biodiversity loss around the world at an unprecedented rate, in what has been deemed the sixth mass extinction. To counteract this crisis, conservationists seek to improve the methods used in the design and implementation of protected areas, which help mitigate the impacts of human activities on species. Marine mammals are ecosystem engineers and important indicator species of ocean and human wellbeing. They are also disproportionally less known and more threatened than terrestrial mammals. Therefore, surrogates of biodiversity must be used to maximize their representation in conservation planning. Some of the most effective surrogates of biodiversity known have only been tested in terrestrial systems. Here I test complementarity, rarity, and environmental diversity as potential surrogates of marine mammal representation at the global scale, and compare their performance against species richness, which is the most popular surrogate used to date. I also present the first map of marine mammal complementarity, and assess its relationship with environmental variables to determine if environmental factors could also be used as surrogates. Lastly, I determine the global complementarity-based hotspots of marine mammal biodiversity, and compare their distributions against current marine protected area coverage and exposure to global indices of human threats, to elucidate the effectiveness of current conservation efforts. Results show that complementarity, rarity, and environmental diversity are all efficient surrogates, as they outcompete species richness in maximizing marine mammal species representation when solving the minimum-set coverage problem. Results also show that sea surface temperature, density, and bathymetry are the top environmental variables most associated with complementarity of marine mammals. Finally, gap analyses show that marine mammals are overall poorly protected, yet moderately exposed to hotspots of cumulative human impacts. The wide distribution of marine mammals justify global studies like the ones here presented, to determine the best strategy for their protection. Overall, my findings show that less popular surrogates of biodiversity are more effective for marine mammals and should be considered in their management, and that the expansion of protected areas in their most important habitats should be prioritized. / Dissertation/Thesis / Doctoral Dissertation Biology 2019

Sedimentation (erosion, transport, and deposition) is a primary and growing environmental, engineering, and agricultural issue around the world. However, collection of the data needed to develop solutions to sedimentation issues has declined by about three-fourths since 1983. Suspended-sediment surrogates have the potential to obtain sediment data using methods that are more accurate, of higher spatial and temporal resolution, and with less manually intensive, costly, and hazardous methods. The improved quality of sediment data from high-resolution surrogates may inform improved understanding and solutions to environmental, engineering, and agricultural sedimentation problems. The field experiments for this research includ physical samples of suspended sediment collected concurrently with surrogate metrics from instruments including 1.2, 1.5, and 3.0 megahertz frequency acoustic doppler current profilers, a nephelometric turbidity sensor, and a laser-diffraction particle size analyzer. This comprehensive data set was collected over five storms in 2009 and 2010 at Yellow River near Atlanta, Georgia. This research project has proposed, developed, and tested a new method for evaluation of sediment size from theoretical acoustic attenuation; evaluated and further developed recently introduced empirical methods for estimating acoustic attenuation by sediment; found and quantified data mischaracterization issues for laser-diffraction metrics; defined deterministic causes for observed hysteresis and variance in suspended sediment to surrogate relations; compared the accuracy of sediment concentration models and loads for each tested surrogate; and compared sediment surrogate technologies on the basis of reliability and operational considerations.

Today's modern aerospace systems exhibit strong interdisciplinary coupling and require a multidisciplinary, collaborative approach. Analysis methods that were once considered feasible only for advanced and detailed design are now available and even practical at the conceptual design stage. This changing philosophy for conducting conceptual design poses additional challenges beyond those encountered in a low fidelity design of aircraft. This thesis takes some steps towards bridging the gaps in existing technologies and advancing the state-of-the-art in aircraft design. The first part of the thesis proposes a new Pareto front approximation method for multiobjective optimization problems. The method employs a hybrid optimization approach using two derivative free direct search techniques, and is intended for solving blackbox simulation based multiobjective optimization problems with possibly nonsmooth functions where the analytical form of the objectives is not known and/or the evaluation of the objective function(s) is very expensive (very common in multidisciplinary design optimization). A new adaptive weighting scheme is proposed to convert a multiobjective optimization problem to a single objective optimization problem. Results show that the method achieves an arbitrarily close approximation to the Pareto front with a good collection of well-distributed nondominated points. The second part deals with the interdisciplinary data communication issues involved in a collaborative mutidisciplinary aircraft design environment. Efficient transfer, sharing, and manipulation of design and analysis data in a collaborative environment demands a formal structured representation of data. XML, a W3C recommendation, is one such standard concomitant with a number of powerful capabilities that alleviate interoperability issues. A compact, generic, and comprehensive XML schema for an aircraft design markup language (ADML) is proposed here to provide a common language for data communication, and to improve efficiency and productivity within a multidisciplinary, collaborative environment. An important feature of the proposed schema is the very expressive and efficient low level schemata. As a proof of concept the schema is used to encode an entire Convair B58. As the complexity of models and number of disciplines increases, the reduction in effort to exchange data models and analysis results in ADML also increases. / Ph. D.

La stabilité des carburants en phase liquide est de premier ordre dans le domaine du transport. Par exemple, les carburants, les lubrifiants ou les additifs doivent être stables de leur production jusqu'à leur utilisation. Cette thèse a pour but de développer et de valider une méthodologie alliant l’acquisition de données expérimentales et le développement de modèles cinétiques pour l'autoxydation en phase liquide.Expérimentalement, une approche complémentaire a été mise en place pour obtenir à la fois des données de réactivité globales via un appareil PetroOxy et des profils d’espèces via un autoclave instrumenté.Numériquement, une méthodologie basée sur un générateur de mécanismes est proposée pour obtenir une chimie détaillée en phase liquide. Les paraffines linéaires et branchées sont étudiées comme des carburants modèles représentatifs de l'autoxidation de carburants réels afin de valider l’approche proposée. Ces familles chimiques sont représentatives de la composition des carburants réels et alternatifs.La réactivité des n-paraffines de C8 à C16 ainsi que d’isomères de l’octane a été étudiée en PetroOxy sur la gamme de température 373-433 K. Puis, des profils d’espèces détaillés de la phase gaz et de la phase liquide ont été obtenus durant l’étude de l’oxydation du n-C8 et du 2-methylheptane dans un autoclave à 383 K et 10 bars. Des mécanismes cinétiques détaillés ont été développé pour toutes les molécules jusqu’à C14. Les mécanismes reproduisent qualitativement la formation des espèces majoritaires lors de l’autoxidation des alcanes ainsi que les tendances observées liées à la longueur de chaîne et la ramification. L’analyse des mécanismes cinétiques a mis en avant le rôle prédominant des radicaux peroxy (ROO) et peroxy-hydroperoxyde (HOOQOO) dans la consommation de carburants modèles.Cette étude a permis d’améliorer la compréhension des processus d’autoxidation des alcanes linéaires et branchés. L’étude de nouveaux systèmes permettra d’améliorer la compréhension globale des processus d’autoxidation et, de réduire l’écart de compréhension existant entre l’autoxidation des carburants réels et des carburants modèles. / Liquid phase stability is a major concern in the transportation and the energy fields. Relevant examples are fuels, lubricants and additives which have to be stable from their production to their application (engine, combustors). This thesis aims to develop and validate a complete methodology combining both experimental data acquisition and the development of kinetic models for liquid phase autoxidation.The experimental methodology is based on a complementary approach to obtain (i) a global reactivity descriptor (Induction Periods) and (ii) detailed species profiles respectively using a PetroOxy device and an instrumented autoclave. Numerically, the presented methodology includes detailed liquid phase mechanisms generation with an automatic mechanism generator (RMG). Normal and iso-paraffins were selected as fuel surrogates for autoxidation to validate the developed methodology. They were selected regarding their large contribution in fuel composition and their growing interest as drop-in fuels.The reactivity of both n-paraffins from C8 to C16 and several C8 iso-paraffins was investigated over a wide temperature range (373-433 K) in the PetroOxy with liquid phase analyses. Then, detailed species profiles from the autoxidation of both n-octane and 2-methylheptane in autoclave were obtained at 383 K and 10 bars. Detailed liquid phase mechanisms were developed for all molecules tested up to C14. Mechanisms qualitatively reproduce the overall phenomenology of the chain length, the branching and the major species profiles observed experimentally. Mechanisms analysis allow to identify the main consumption pathways of alkanes through peroxy (ROO) and peroxy-hydroperoxide radicals (HOOQOO) over the temperature range investigated (373-473 K).This study permitted to increase the comprehension of autoxidation processes involved in normal and branched alkanes. The study of new chemical systems will increase the global comprehension of autoxidation processes and in fine it will reduce the gap between the current autoxidation knowledge and the real fuel autoxidation.

Linear digital signal processing based around linear, time-invariant systems theory finds substantial application in speech processing. The linear acoustic source-filter theory of speech production provides ready biomechanical justification for using linear techniques. Nonetheless, biomechanical studies surveyed in this thesis display significant nonlinearity and non-Gaussinity, casting doubt on the linear model of speech production. In order therefore to test the appropriateness of linear systems assumptions for speech production, surrogate data techniques can be used. This study uncovers systematic flaws in the design and use of exiting surrogate data techniques, and, by making novel improvements, develops a more reliable technique. Collating the largest set of speech signals to-date compatible with this new technique, this study next demonstrates that the linear assumptions are not appropriate for all speech signals. Detailed analysis shows that while vowel production from healthy subjects cannot be explained within the linear assumptions, consonants can. Linear assumptions also fail for most vowel production by pathological subjects with voice disorders. Combining this new empirical evidence with information from biomechanical studies concludes that the most parsimonious model for speech production, explaining all these findings in one unified set of mathematical assumptions, is a stochastic nonlinear, non-Gaussian model, which subsumes both Gaussian linear and deterministic nonlinear models. As a case study, to demonstrate the engineering value of nonlinear signal processing techniques based upon the proposed biomechanically-informed, unified model, the study investigates the biomedical engineering application of disordered voice measurement. A new state space recurrence measure is devised and combined with an existing measure of the fractal scaling properties of stochastic signals. Using a simple pattern classifier these two measures outperform all combinations of linear methods for the detection of voice disorders on a large database of pathological and healthy vowels, making explicit the effectiveness of such biomechanically-informed, nonlinear signal processing techniques.

Made available in DSpace on 2016-06-02T19:30:11Z (GMT). No. of bitstreams: 1 6647.pdf: 3348146 bytes, checksum: 2a91ad90e181871a3f0cd04d215a295b (MD5) Previous issue date: 2015-03-09 / Universidade Federal de Sao Carlos / The growing world interest for the Amazon region has risen up the most diverse issues. Among these are those of ecological importance, to promote the conservation and maintenance of natural resources of the region. It was intended to, in this study, analyze the structure of the zooplankton community and its spatial distribution and temporal patterns on the Madeira River and tributaries in the area of influence of the Santo Antônio HPP, before, during and after their deployment, to verify the occurrence possible changes. Quarterly samplings were carried out for four years for the physical and chemical variables and zooplankton. The zooplankton community structure varied widely depending on the hydrological events, but was little changed after filling the reservoir probably because the HPP be of the run-of-river type. Changes in the density of zooplankton were lower than those observed in large accumulation reservoir previously built in the Amazon. However there have been changes in the proportions of biomass of different zooplankton groups. Whereas the functional approach, in all analyzed rivers was observed that before the filling had greater selection of r strategists and smaller species and after filling greater numbers of functional groups coexisted. In relation to the components of diversity, greater evenness values were recorded in the last years of sampling. For other functional and taxonomic indices (richness, Shannon, FDis and FEev), differences related to impoundment on the Madeira River were not verified. Considering the approach of surrogates, the amounts recorded for analysis of concordance between the zooplankton community groups and also among the taxonomic classification levels were low significance, which prevents them from being used separately in biomonitoring studies in the region. We conclude that the Madeira River and its tributaries have high zooplankton diversity and until the moment the changes in the community were low, presumably by maintaining the short residence time. The results show that different approaches, both functional as taxonomic, evaluated together, can be a great step toward understanding the relationship between environmental standards, management practices and production of ecosystem services. / O crescente interesse mundial pela região Amazônica tem levantado diversas questões, dentre elas as de importância ecológica, visando a conservação e manutenção dos recursos naturais da região. Pretendeu-se, no presente estudo, analisar a estrutura da comunidade zooplanctônica e seus padrões de distribuição espacial e temporal no rio Madeira e tributários na área de influência da UHE de Santo Antônio, antes, durante e após a sua implantação, visando verificar a ocorrência de possíveis alterações. Foram realizadas amostragens trimestrais durante o período de 2009 a 2013, para as variáveis físicas, químicas e do zooplâncton. A estrutura da comunidade variou amplamente em função dos eventos hidrológicos, mas foi pouco alterada após o enchimento do reservatório provavelmente pelo fato da usina ser do tipo fio d água. As mudanças na densidade do zooplâncton foram menores do que as observadas nos grandes reservatórios de acumulação anteriormente construídos na Amazônia. Contudo ocorreram mudanças nas proporções da biomassa dos diferentes grupos zooplanctônicos. Considerando a abordagem funcional, em todos os rios analisados observou-se que durante a fase pré-enchimento havia maior seleção de espécies r estrategistas e de menor tamanho e que após o enchimento um maior número de grupos funcionais coexistiu. Em relação aos componentes da diversidade, maiores valores de equitabilidade foram registrados nos últimos anos de amostragem. Para os demais índices funcionais e taxonômicos (riqueza, Shannon, FDis e FEev), diferenças relacionadas ao barramento do rio Madeira não foram verificadas. Pela abordagem de grupos substitutos, os valores de concordância obtidos entre os grupos zooplanctônicos e também entre os níveis de classificação taxonômica foram de baixa significância, o que impede que estes possam ser usados separadamente no biomonitoramento da região. Conclui-se que o rio Madeira e seus tributários estudados detêm elevada diversidade zooplanctônica e que até o momento as alterações na comunidade foram baixas, provavelmente pela manutenção do curto tempo de residência. Os resultados mostram que diferentes abordagens, tanto funcionais como taxonômicas, avaliadas em conjunto, podem constituir uma ferramenta valiosa em direção à compreensão da relação entre padrões ecológicos, práticas de manejo e produção de serviços ecossistêmicos.

In this thesis, the authors investigate how machine learning can be utilized for speeding up the design optimization process of gas turbines. The Finite Element Analysis (FEA) steps of the design process are examined if they can be replaced with machine learning algorithms. The study is done using a component with given constraints that are provided by Siemens Energy AB. With this component, two approaches to using machine learning are tested. One utilizes design parameters, i.e. raw floating-point numbers, such as the height and width. The other technique uses a high dimensional mesh as input. It is concluded that using design parameters with surrogate models is a viable way of performing design optimization while mesh input is currently not. Results from using different amount of data samples are presented and evaluated.

<p>Injection to the subcutaneous (SC) tissue is one of the preferred methods for drug delivery of pharmaceuticals, from small molecules to monoclonal antibodies. Delivery to SC has become widely popular in part thanks to the low cost, ease of use, and effectiveness of drug delivery through the use of auto-injector devices. However, injection physiology, from initial plume formation to the eventual uptake of the drug in the lymphatics, is highly dependent on SC mechanics, poroelastic properties in particular. Yet, the poroelastic properties of SC have been understudied. In this thesis, I present a two-pronged approach to understanding the poroelastic properties of SC. Experimentally, mechanical and fluid transport properties of SC were measured with confined compression experiments and compared against gelatin hydrogels used as SC-phantoms. It was found that SC tissue is a highly non-linear material that has viscoelastic and porohyperelastic dissipation mechanisms. Gelatin hydrogels showed a similar, albeit more linear response, suggesting a micromechanical mechanism may underline the nonlinear behavior. The second part of the thesis focuses on the multiscale modeling of SC to gain a fundamental understanding of how geometry and material properties of the microstructure drive the macroscale response. SC is composed of adipocytes (fat cells) embedded in a collagen network. The geometry can be characterized with Voroni-like tessellations. Adipocytes are fluid-packed, highly deformable and capable of volume change through fluid transport. Collagen is highly nonlinear and nearly incompressible. Representative volume element (RVE) simulations with different Voroni tesselations shows that the different materials, coupled with the geometry of the packing, can contribute to different material response under the different kinds of loading. Further investigation of the effect of geometry showed that cell packing density nonlinearly contributes to the macroscale response. The RVE models can be homogenized to obtain macroscale models useful in large scale finite element simulations of injection physiology. Two types of homogenization were explored: fitting to analytical constitutive models, namely the Blatz-Ko material model, or use of Gaussian process surrogates, a data-driven non-parametric approach to interpolate the macroscale response.</p>

In der nichtlinearen Datenreihenanalyse hat sich seit etwa 10 Jahren eine Monte-Carlo-Testmethode etabliert, die Theiler-surrogatmethode, mit Hilfe derer entschieden werden kann, ob eine Datenreihe nichtlinearen Ursprungs sei. Diese Methode wird kritisiert, modifiziert und verallgemeinert. Das, was Theiler untersuchen will braucht andere Surrogatmethoden, die hier konstruiert werden. Und das, was Theiler untersucht braucht gar keine Monte-Carlo-Methoden. Mit Hilfe des in der Arbeit eingeführten Begriffs des Phasensignals werden Testmöglichkeiten dargelegt und Beziehungen zwischen den nichtlinearen Eigenschaften der Zeitreihe und deren Phasenspektrum erforscht. Das Phasensignal wird aus dem Phasenspektrum der Zeitreihe hergeleitet und registriert außerordentliche Geschehnisse im Zeitbereich sowie Phasenkopplungen im Frequenzbereich. <br /> <br /> Die gewonnenen Erkenntnisse werden auf das Problem der Polbewegung angewendet. Die Hypothese einer nichtlinearen Beziehung zwischen der atmosphärischen Erregung und der Polbewegung wird untersucht. Eine nichtlineare Behandlung wird nicht für nötig gehalten. / In the nonlinear data analysis there is a popular Monte Carlo Test method due to Theiler (it was established about 10 years ago), the Theiler surrogate method, which tests whether a time series is of a linear origin. This method is being criticized, modified and generalized in this thesis. What Theiler wants to test, needs other surrogate methods, which are constructed here. And what Theiler really tests, does not need Monte Carlo methods. With the help of the concept of the phase signal, that is introduced here, other test options are possible. The phase signal helps also in investigating the relations between the nonlinear characteristics of the time series and their phase spectrum. The phase signal is derived from the phase spectrum of the time series and registers extraordinary events in the time domain as well as phase couplings in the frequency domain. <br /> <br /> These theoretical approches are applied to the problem of polar motion. The hypothesis of a nonlinear relationship between the atmospheric excitation and the pole movement is examined. A nonlinear treatment is not considered necessary.