The purpose of this research is to investigate the influence of stitching architectures by using different stitching periodic patterns on the in-plane and out-of-plane mechanical properties. By using the inherent periodic architecture of these composites, their mechanical properties may be tailored for specific applications. Composite structures are extensively used in several industries such as aerospace, automotive, sports, and construction due to their many advantages, which include tailorable mechanical properties, high strength-to-weight ratios, and high specific stiffness. However, due to their low interlaminar tensile strength, composites are prone to delaminations, which can degrade the overall mechanical performance of the structure. Through-thickness stitching provides the third-direction reinforcement to enhance the interlaminar tensile and shear strengths. In this study, quasi-isotropic composite test articles were manufactured and stitched through-thickness using different chain stitch patterns. Full-field surface strain measurements were collected through the non-contact digital image correlation (DIC) technique. A design of experiments (DoE) approach was used to investigate the stitch parameters, such as stitch density (number of stitches per unit area), stitch angle (stitch seam orientation), and linear thread density (thread diameter), and their interactions on the in-plane and out-of-plane mechanical properties. Experimental results are then used to develop a statistically informed response surface model (RSM) to find optimal stitching parameters based on a maximum predicted tensile strength, tensile modulus and flexural strength.

Work in this dissertation is motivated by reducing the design cost at the early design stage while maintaining high design accuracy throughout all design stages. It presents four key design methods to improve the performance of Efficient Global Optimization for multidisciplinary problems. First, a fidelity-calibration method is developed and applied to lower-fidelity samples. Function values analyzed by lower fidelity analysis methods are updated to have equivalent accuracy to that of the highest fidelity samples, and these calibrated data sets are used to construct a variable-fidelity Kriging model. For the design of experiment (DOE), a dynamic sampling method is developed and includes filtering and infilling data based on mathematical criteria on the model accuracy. In the sample infilling process, multi-objective optimization for exploitation and exploration of design space is carried out. To indicate the fidelity of function analysis for additional samples in the variable-fidelity Kriging model, a dynamic fidelity indicator with the overlapping coefficient is proposed. For the multidisciplinary design problems, where multiple physics are tightly coupled with different coupling strengths, multi-response Kriging model is introduced and utilizes the method of iterative Maximum Likelihood Estimation (iMLE). Through the iMLE process, a large number of hyper-parameters in multi-response Kriging can be calculated with great accuracy and improved numerical stability. The optimization methods developed in the study are validated with analytic functions and showed considerable performance improvement. Consequentially, three practical design optimization problems of NACA0012 airfoil, Multi-element NLR 7301 airfoil, and all-moving-wingtip control surface of tailless aircraft are performed, respectively. The results are compared with those of existing methods, and it is concluded that these methods guarantee the equivalent design accuracy at computational cost reduced significantly. / Doctor of Philosophy / In recent years, as the cost of aircraft design is growing rapidly, and aviation industry is interested in saving time and cost for the design, an accurate design result during the early design stages is particularly important to reduce overall life cycle cost. The purpose of the work to reducing the design cost at the early design stage with design accuracy as high as that of the detailed design. The method of an efficient global optimization (EGO) with variable-fidelity analysis and multidisciplinary design is proposed. Using the variable-fidelity analysis for the function evaluation, high fidelity function evaluations can be replaced by low-fidelity analyses of equivalent accuracy, which leads to considerable cost reduction. As the aircraft system has sub-disciplines coupled by multiple physics, including aerodynamics, structures, and thermodynamics, the accuracy of an individual discipline affects that of all others, and thus the design accuracy during in the early design states. Four distinctive design methods are developed and implemented into the standard Efficient Global Optimization (EGO) framework: 1) the variable-fidelity analysis based on error approximation and calibration of low-fidelity samples, 2) dynamic sampling criteria for both filtering and infilling samples, 3) a dynamic fidelity indicator (DFI) for the selection of analysis fidelity for infilled samples, and 4) Multi-response Kriging model with an iterative Maximum Likelihood estimation (iMLE). The methods are validated with analytic functions, and the improvement in cost efficiency through the overall design process is observed, while maintaining the design accuracy, by a comparison with existing design methods. For the practical applications, the methods are applied to the design optimization of airfoil and complete aircraft configuration, respectively. The design results are compared with those by existing methods, and it is found the method results design results of accuracies equivalent to or higher than high-fidelity analysis-alone design at cost reduced by orders of magnitude.

Approved for public release; distribution is unlimited / The US Department of Defense is currently pursuing the most comprehensive transformation of its forces since the early years of WWII. This transformation is a holistic approach to update both the equipment that the forces will fight its conflicts with and the way in which they will fight. This transformation relies heavily on fully networked air, ground and space based platforms. While many experts agree that in the course of the next 10 years communications equipment will emerge to support the networking of these systems, there remains much uncertainty on how operations will be effected if the technology does not mature enough to meet expectations. This research shows that even a 25 percent degradation in communications range could pose significant challenges for this Future Force. Additionally, even small delays (latencies greater than one minute) and constraints on network throughput can increase the Future Force casualties and the duration of battle. While the end result in all analysis shows that the Future Force is a superior element with the same battle end state-victory, the cost of that victory depends significantly on effective communications. / Captain, United States Army

Approved for public release, distribution is unlimited / Recent insurgent tactics during Operation Iraqi Freedom (OIF) have demonstrated that coalition logistical convoys are vulnerable targets. This thesis examines the tactics, techniques and procedures (TTPs) used in convoy operations in an attempt to identify the critical factors that lead to mission success. A ground convoy operation scenario is created in the agentbased model (ABM) Map Aware Non-uniform Automata (MANA). The scenario models a generic logistical convoy consisting of security vehicles, logistical vehicles, an unmanned aerial vehicle (UAV) and an enemy ambushing force. The convoy travels along a main supply route (MSR) where it is ambushed by a small insurgent force. We use military experience, judgment and exploratory simulation runs to identify 11 critical factors within the created scenario. The data farming process and Latin Hypercube (LHC) experimental design technique are used to thoroughly examine the 11 factors. Using the 11 factors 516 design points are created and data farmed over to produce 25,800 observations. Additive multiple linear regression is used to fit a model to the 25,800 observations. From the created scenario it is concluded that: convoy mission success may be determined by only a few factors; the actions of logistical vehicles are more critical than those of security vehicles; UAVs provide a statistically significant advantage; and ABMs coupled with LHCs and data farming are valuable tools for understanding complex problems. / Captain, United States Marine Corps

Approved for public release; distribution is unlimited / To ensure sufficient capacity to handle unexpected demands for electric power, decision makers often over-estimate expeditionary power requirements. Therefore, we often use limited resources inefficiently by purchasing more generators and investing in more renewable energy sources than needed to run power systems on the battlefield. Improvement of the efficiency of expeditionary power units requires better managing of load requirements on the power grids and, where possible, shifting those loads to a more economical time of day. We analyze the performance of a previously developed optimization model for scheduling time-shiftable electrical loads in an expeditionary power grids model in two experiments. One experiment uses model data similar to the original baseline data, in which expected demand and expected renewable production remain constant throughout the day. The second experiment introduces unscheduled demand and realistic fluctuations in the power production and the demand distributions data that more closely reflect actual data. Our major findings show energy grid power production composition affects which uncertain factor(s) influence fuel con-sumption, and uncertainty in the energy grid system does not always increase fuel consumption by a large amount. We also discover that the generators running the most do not always have the best load factor on the grid, even when optimally scheduled. / Lieutenant Commander, United States Navy

L’augmentation de la densité d’intégration des circuits intégrés nous a amené à étudier, dans le cadre du développement de la technologie CMOS 45 nm, les sources de variabilité inhérentes aux procédés de fabrication utilisés pour ce nœud technologique, et à en déterminer les composantes principales,dans le but ultime de permettre la simulation précise de l’impact de la variabilité technologique à la fois au niveau transistor et circuit. Après un état de l’art des sources de variabilité du transistor MOS et des moyens de simulation associés,ce travail s'est orienté sur les fluctuations d'un facteur technologique difficilement accessible à la mesure statistique qu'est le dopage canal. Ensuite le nœud 45 nm a été étudié expérimentalement via un plan d'expériences.Ceci a permis de connaitre les variations naturelles des facteurs technologiques mais surtout les sensibilités des performances électriques vis-à-vis de ces facteurs.Nous avons pu ainsi identifier les causes prépondérantes de variabilité dues au procédé.Enfin, nous proposons d’améliorer la prise en compte des déviations des facteurs process dans les simulations Monte-Carlo et pire-cas appliquées aux modèles compacts au regard de ces observations expérimentales. / Continuous improvement in integrated circuits density of integration lead us to study process-induced variations in the framework of the 45 nm node, and to determine their principal contributions with the ultimate goal being to allow an accurate simulation of both transistor and circuit level variability. This work starts with a study of the state of the art of variability sources of the MOS transistor and associated simulation means. Then it focuses on the fluctuations of the channel doping, which is a difficult factor to measure statistically.After that we study the 45 nm node through a design of experiment which let us learn about natural variations of process factors but mostly about electrical performances sensitivity to those factors.Thanks to that we could identify major causes of process-induced variability at this stage of this node development. At last, with respect to those experimental results, we propose to enhance the taking in account of process variations in Monte-Carlo and corner simulations applied to compact models.

Les grandes entreprises ferroviaires intègrent au niveau du matériel roulant une grande variété de systèmes complexes qui se doivent d’être fiables et ce, dès le démarrage du service commercial. Ce travail de thèse propose une méthodologie expérimentale pour l’amélioration de la robustesse d’un système prédominant, à savoir l’accès voyageurs. L'objectif est d'améliorer sa fiabilité intrinsèque dans un laps de temps raisonnable dans le cadre de projet industriel contraint par le temps. La méthodologie expérimentale proposée s’appuie sur la méthode des essais aggravés et accélérés de fiabilité, et se veut être optimisée grâce à l’utilisation de plans d’expériences D-optimaux. Après une analyse bibliographique, suivie d’une étude sur l’utilisation des plans d’expériences D-optimaux, ce travail expose les méthodes et moyens expérimentaux mis en place pour utiliser les plans d’expériences dans un contexte industriel. La dernière partie de cette thèse contient les résultats quantitatifs et qualitatifs issus des expérimentations réaliséessur le banc d'essais du système accès voyageurs développé par Bombardier. / The train manufacturer companies handle a large number of complex systems in their trains. These systems must be reliable to ensure reliability of the final product as soon the entry into commercial services. This thesis provides an experimental solution to improve robustness of a predominate system, namely passengers access system. The goal is to improve inherent reliability in a reasonable amount of time to be integrated in a project phase. This experimental method is based on testing aggravated and accelerated method temporally optimized with using of D-optimal design of experiment. After a literature review, followed by a focus on the definition and use of experimental design D-optimal, this work will present experimental methods and means used to set up the experimental design in an industrial context. The last part of this thesis contains quantitative and qualitative results performed on the passenger’s access test bench developed by Bombardier.

L’utilisation d’adhésifs polyépoxy et plus particulièrement de pâte de calage dans l’aéronautique est chose très courante. L’augmentation des cadences de production des aéronefs poussent les fournisseurs à adapter les temps technologiques de ces produits (temps d’application et de complète polymérisation) : ainsi, la cinétique de réticulation des adhésifs de demain devra être lente à température ambiante et pouvant être accélérée à tout moment. Pour cela, la piste envisagée pour ces tra-vaux est la polymérisation sous rayonnement infrarouge. La cinétique de ré-action a été évaluée par analyse thermique (DSC) ou par analyse spectrosco-pique (MIR ou PIR). Les résultats obtenus ont mis en évidence un effet thermique et non thermique du rayonnement infrarouge. Grâce à plusieurs expérimentations, les résultats montrent que le rayonnement infrarouge interagit avec les groupe-ments époxydes dont l’énergie d’activation de la réaction avec les amines primaires diminue. Par ailleurs, l’utilisation d’un plan d’expérience a permis de montrer que l’adhérence et les propriétés mécaniques de ces adhésifs augmentaient suite à l’utilisation du rayonnement infrarouge. / The use of polyepoxy adhesives and more particularly of liquid shim in aero-nautics is very common. The increase in aircraft production rates is pushing suppli-ers to adapt the technological times of these sort of products (application and complete curing times): thus, the curing kinetics of tomorrow's adhesives must be slow at room temperature and can be accelerated at any time. For this purpose, this work paves the way of an infrared curing. The reaction kinetics were evalu-ated by thermal analysis (DSC) or spectroscopic analysis (MIR or NIR). The results obtained showed a thermal and non-thermal effects of infrared radiation. Thanks to several experiments, the results show that infrared radiation interacts with epoxide groups whose activation energy with primary amines reaction decreas-es. In addition, by the use of Design of Experiment (DoE) showed that the ad-hesion and mechanical properties of these adhesives increased as a result of the use of infrared radiation.

Os protetores solares (PS) são os grandes responsáveis pela proteção da pele quando exposta à radiação solar, por isso a importância sanitária de se otimizar o desenvolvimento deste cosmético tipo II e monitorar para que seja eficaz em seu propósito. O principal objetivo deste trabalho é aplicar os conceitos de Qualidade por Design (QbD), ferramentas estatísticas de desenho experimental (DoE - Design of Experiments) e o conceito de tecnologia analítica de processo (PAT - Process Analytical Technology) para desenvolver uma formulação e processo produtivo de um PS de modo a modernizar os processos da indústria cosmética, fazendo as análises durante o processo e eliminando o controle de qualidade final. Trata-se de um sistema de desenvolvimento sistematizado, onde se executa as ferramentas de QbD para avaliar os dados obtidos ao longo da fase experimental. Para a fase experimental, empregou-se o desenho fatorial e desenho do compósito central (CCD - Central Composite Design) como ferramenta estatística, para a execução do planejamento de experimentos (DoE - Design of Experiments). As respostas foram analisadas através da metodologia de superfície resposta (RSM - Response Surface Methodology). Tais ferramentas são fundamentais para a determinação do desenho de concepção (design space), para se obter o PS com as melhores características físico-químicas e de processo dentro do escopo delineado. Para o desenvolvimento da metodologia de análise in line, optou-se pela utilização da espectrometria UV, utilizando-se ferramentas como análise de regressão dos mínimos quadrados (PLS) devido a praticidade em transforma-la em uma ferramenta PAT, para isto, a quimiometria foi empregada para modelar sistemas que são desconhecidos e complexos, como um PS, e trazendo respostas diretas como a aprovação do produto antes de ser embalado, por exemplo. A abordagem apresentada baseia-se na construção da qualidade ao longo do desenvolvimento e otimização de PS e torna possível o monitoramento da qualidade em tempo real. / The sunscreens are great responsible for the skin protection when it is exposed to direct sunlight, so it means a great importance of health to optimize the development of type II cosmetic and monitor for it to be effective in its purpose. The objective of this work is to apply the concepts of Quality by Design and statistical tools of experimental design (DoE - Design of experiments), as well as applying the process analytical technology (PAT - Process Analytical Technology) concept for formulation and manufacturing process development of a topical sunscreen being able to modernize the cosmetic industry processing, including real time analyses and eliminating quarantine step, which waits analysis approval performed by the quality assurance, and then release the product for sale. As it is a systematic development, where critical quality attributes and risk assessment were performed to evaluate over obtained data. During experimental phase, the factorial design was used as a statistical tool for design of experiments implementation, and the responses were analyzed by response surface methodology (RSM - Response Surface Methodology). This mapping is critical to determination of the product design (design space), i.e. get sunscreen with the best physical and chemical characteristics and processing within the outlined scope. For in line methodology development, UV spectrometry was opted to be used due to less effort in sample preparation and due to great easiness to turn it into a PAT tool. For this, chemometrics was used, which brings together chemical and statistical elements to obtain three main elements: empirical modeling, multivariate modeling and chemical data, making it able to model systems that are unknown and complex, as a sunscreen, getting direct answers as product release approval before being packed, for example. The presented approach was based on the construction of quality throughout the sunscreen development and optimization making possible the real time quality monitoring.

Polímeros híbridos são caracterizados por conter numa mesma partícula dois tipos diferentes de polímero, normalmente incompatíveis e ligados por ligações covalentes. Neste trabalho, a síntese de um polímero híbrido acrílico-alquídico pelo processo de miniemulsão foi investigada. Com o objetivo de compreender como diferentes variáveis na fórmula afetam as características físico-químicas finais do látex, um planejamento experimental foi desenhado com o auxílio do software DX9 e os resultados analisados por modelos empíricos de superfície de resposta. Os fatores variados (variáveis independentes) foram: quantidade de co-estabilizante, surfactante e iniciador. Cada um dos fatores contribuiu para a alteração de pelo menos uma característica avaliada, e a sinergia entre eles afeta diretamente o teor de RDG, resposta indicativa do grau de grafitização entre as espécies. O coestabilizante contribuiu para o aumento do diâmetro médio de gotas e da polidispersidade de tamanho de partículas, enquanto reduziu a dureza do filme. A concentração de surfactante alterou o número de partículas por litro, reduzindo o diâmetro médio de partículas e aumentando a polidispersidade. O iniciador aumentou a conversão monomérica. Todas as dispersões de polímero híbrido produzidas apresentaram redução do tamanho médio de gotas para partículas, indicando evidência de nucleação secundária. As avaliações por microscopia eletrônica de transmissão (TEM) e microscopia de força atômica (AFM) mostraram que a morfologia obtida é do tipo núcleo-casca. / Hybrid polymers are defined by the presence of two or more different kinds of polymers in the same particle, typically incompatible and linked by covalent bonds. In this work, the synthesis of an alkyd-acrylic hybrid polymer produced by miniemulsion polymerization has been investigated. With the goal of understanding how different variables in the recipe affect the final characteristics of the latex, a design of experiment was planned using DX9 software and the results were analyzed by response surface methodology. The factors studied (independent variables) were: amount of co-stabilizer, surfactant and initiator. Each of these factors contributed to change at least one of the evaluated characteristics, and the synergy between them directly affects the RDG content, response of the polymer degree of grafting. Costabilizer contributed to increase the average droplets diameter and polydispersity of particle size, while reducing the film hardness. The amount of surfactant changed the number of particles, reducing the average particle size and increasing polydispersity. Initiator increased the monomer conversion. All hybrids dispersions presented a decrease in the droplet size to particle size, indicating evidence of secondary nucleation. Core-shell morphology was observed through transmission electron microscopy (TEM) and atomic force microscopy (AFM).