Design optimization of modern machine drive systems for maximum fault tolerant and optimal operation

Modern electric machine drives, particularly three phase permanent magnet machine drive systems represent an indispensable part of high power density products. Such products include; hybrid electric vehicles, large propulsion systems, and automation products. Reliability and cost of these products are directly related to the reliability and cost of these systems. The compatibility of the electric machine and its drive system for optimal cost and operation has been a large challenge in industrial applications. The main objective of this dissertation is to find a design and control scheme for the best compromise between the reliability and optimality of the electric machine-drive system. The effort presented here is motivated by the need to find new techniques to connect the design and control of electric machines and drive systems. ^ A highly accurate and computationally efficient modeling process was developed to monitor the magnetic, thermal, and electrical aspects of the electric machine in its operational environments. The modeling process was also utilized in the design process in form finite element based optimization process. It was also used in hardware in the loop finite element based optimization process. The modeling process was later employed in the design of a very accurate and highly efficient physics-based customized observers that are required for the fault diagnosis as well the sensorless rotor position estimation. Two test setups with different ratings and topologies were numerically and experimentally tested to verify the effectiveness of the proposed techniques. ^ The modeling process was also employed in the real-time demagnetization control of the machine. Various real-time scenarios were successfully verified. It was shown that this process gives the potential to optimally redefine the assumptions in sizing the permanent magnets of the machine and DC bus voltage of the drive for the worst operating conditions. ^ The mathematical development and stability criteria of the physics-based modeling of the machine, design optimization, and the physics-based fault diagnosis and the physics-based sensorless technique are described in detail. ^ To investigate the performance of the developed design test-bed, software and hardware setups were constructed first. Several topologies of the permanent magnet machine were optimized inside the optimization test-bed. To investigate the performance of the developed sensorless control, a test-bed including a 0.25 (kW) surface mounted permanent magnet synchronous machine example was created. The verification of the proposed technique in a range from medium to very low speed, effectively show the intelligent design capability of the proposed system. Additionally, to investigate the performance of the developed fault diagnosis system, a test-bed including a 0.8 (kW) surface mounted permanent magnet synchronous machine example with trapezoidal back electromotive force was created. The results verify the use of the proposed technique under dynamic eccentricity, DC bus voltage variations, and harmonic loading condition make the system an ideal case for propulsion systems.^

Multi-objective optimization of the molecular structure of refrigerants

The aim of this work was to develop a new methodology, which can be used to design new refrigerants that are better than the currently used refrigerants. The methodology draws some parallels with the general approach of computer aided molecular design. However, the mathematical way of representing the molecular structure of an organic compound and the use of meta models during the optimization process make it different. In essence, this approach aimed to generate molecules that conform to various property requirements that are known and specified a priori. A modified way of mathematically representing the molecular structure of an organic compound having up to four carbon atoms, along with atoms of other elements such as hydrogen, oxygen, fluorine, chlorine and bromine, was developed. The normal boiling temperature, enthalpy of vaporization, vapor pressure, tropospheric lifetime and biodegradability of 295 different organic compounds, were collected from open literature and data bases or estimated. Surrogate models linking the previously mentioned quantities with the molecular structure were developed. Constraints ensuring the generation of structurally feasible molecules were formulated and used in commercially available optimization algorithms to generate molecular structures of promising new refrigerants. This study was intended to serve as a proof-of-concept of designing refrigerants using the newly developed methodology.

A conceptualização de RAIVA na perspectiva da Teoria Cognitiva da Metáfora: uma análise da emergência de sentido

The objective of this research is to describe and analyze in literary corpus, the way we conceptualize emotions, especially anger. Using the assumptions of the call Cognitive Theory of Metaphor, present a general overview of cognition metaphor on the basis of Cognitive Linguistics, and in a deeper way, we analyze the metaphorical conceptualization of anger. The proposal embodied mind, prevalent in current cognitive science, is fundamental for studies involving mental simulation. Recent research shows that the metaphor is the result of cognitive processes that involve our perception sensorimotor combined with socio-cultural experiences. The ability to build via frequency standards for our experiments is crucial to our language, including metaphorical constructions. Such constructions are the result of cognitive processes that involve the relationship between image schemas and frames. Image schemas comes from our sensorimotor experience, which lists the limits of our bodies to the limits of our surroundings, and frames, in turn, comes from our ability to stock sociocultural events. The metaphorical construction is the result of this constant relationship between body, mind and culture, situating us in bodily experiences and cultural. By analyzing five national literary works, we created an analytical framework on how anger is understood, specifically in Portuguese language. The results are important to understand, through language, how culture is part of our cognition, in conjunction with the sensorimotor aspects.

Identidades coletivas de estudiosos da linguagem no currículo lattes: docência, pertença social e capital cultural-acadêmico

The discussion involving the identity of social actors has taken place for some years, however, it has become significant for the discourse studies over the last years due to the fragmentation of postmodern actors. Understanding the identity as a symbolic concept that can aid in the detection of certain realities - a kind of mechanism / a magnifying glass (MERLUCCI, 1985) - you can check the linguistic materiality of the introductory text of the lattes resume as a adequate place for the formation of collective identities . The aim of this dissertation is to reflect, in a time of postmodernity, through the lattes introductory curriculum texts, the collective identities of the language researchers are portrayed in discursive and social practices based on the accumulation of cultural and academic capital. For analysis, surrounding the indisciplinary posture in Applied Linguistics (MOITA-LOPES, 2006), the descriptive / interpretive methodology was used (MAGALHÃES, 2001). Whereas the study method and the social theory, as state reasons of the research makes use of the Sociological Approach and Communicational Discourse, chain linked to the assumptions of Critical Discourse Analysis (PEDROSA, 2012a). The corpus is constituted of twenty-seven introductory texts from the lattes curriculum of language researchers, connected to three institutions of higher learning in Sergipe. After the collection, on the lattes platform, and the numbering of the curriculum in order to achieve the research objective, we performed the analysis based on three identity themes: teaching, social belonging (BAJOIT, 2006; DESCHAMPS; MOLINER, 2009) and the accumulation of academic-cultural capital (BOURDIEU, 2004; HEY, 2008). The data show that the texts of the lattes curriculum are based on hegemonic and ideological principals, referring to the accumulation of academic assets, the valuation of actors and the hierarchical positions, recognized and ratified by couples who socialize among themselves Right now, the research allows us to infer that, in postmodernity, some collective identity assumptions, contribute to the understanding of the academic reality, around the the lattes curriculum.

Minicontos: uma prática de letramento emergente na escola

Like numerous other mini ficçion genres, the Flash fiction is configured as a concise and brief genre, but it can still preserve some elements of the traditional tale, such as: narrator, space-temporal unit, characters and plot. For some authors, the emergence of this genre is strictly connected to the speed and diversity of forms of communication in the current social context, that require the reader other skills in addition to reading and writing. Considering the importance of these skills in a literate society and recognizing this genre as potentially effective tool for the development of literacy, this research has as objective to describe the development and implications of didactic sequence directed the literacy practices with the Flash fiction genre. Thus, the research becomes effective in an elementary school vespertine class in 9th grade from Escola Estadual Dr. José Gonçalves de Medeiros, located in the city of Acari-RN. As theoretical assumptions, it will be used fundamentals from Literacy Studies as social practice, especially that ones discussed by the writings Kleiman (1995), Hamilton (2000), Soares (2012), Mortatti (2004) and Rojo (2012). To subsidize the literary literacy, it will be used the theoretical contibutions of Borges (2000), Candido (2004), Pinheiro (2001) and Silva e Silveira (2013). In what relates to the study about the storytellers, it was taken by support the postulates of Gotlib (2006), Bosi (1997), Cortázar (1999), Talbot (2002), Poe (s/d), Luzia de Maria (2004), as well as studies by researchers and writers as Spalding (2007; 2008; 2011), George (2007), Freire (2004) and Trevisan (1994), among others who are dedicated to study Flash fiction. In the methodological field, the proposed perspective anchors itself in an action-researching guidelines (MOREIRA; CALEFFE, 2006) and in the approach of a qualitative data (BOGDAN; BIKLEN, 1994), since it talks to interpretation of diagnosed situation, implementation of intervention actions organized in didactic sequence (SCHNEUWLY; DOLZ, 2004; BARROS; RIVERS-registry, 2014), including description and evaluation of results achieved from the implementation of such actions. The discussions generated indicate that the work with Flash ficition, developed by means of didactic sequences, contributes to the reflection on teaching strategies of Portuguese, used to prepare the students to meet the demands of reading and writing of contemporary society.

A correlação locução adjetiva/adjetivo: uma análise funcional

This research deals with the relationship locução adjetiva / adjective, focusing the reasons for using one form or the other one, in situations where the speaker has a choice between an adjective or a locução adjetiva virtually correspondent and vice versa. In general, the objective is to investigate the possibility of correlation between locução adjetiva and adjective, and to identify motivations for the use of one form or the other one. The theoretical support of this paper is the Linguística Funcional Centrada no Uso (LFCU), which groups together theoretical and methodological assumptions of North American Functional Linguistics, represented by authors as Givón (1984), Bybee (2010), Traugott (2011), and Cognitive Linguistics, as developed by Lakoff (1987), Langacker (1987) and Lakoff and Johnson (2002). As regards the methodological procedures, this research is of qualitative and quantitative character: at first, we did the survey data in the texts that made up the corpus, followed by analysis of each them, especially the locução adjetiva, by considering the semantic, morphosyntactic, cognitive and pragmatic aspects. The corpus is composed of 36 texts, taken from 12 issues of the Veja magazine, published between January 2013 and March 2013. As for the results, in the case of locução adjetiva with related adjectives, this research has shown that the choice of former is due to semantic change, the use of lexicalized forms, to priming cases or to stylistic motivations. It means that the choices of one of these two forms go beyond lexical issues, since there are other motivations, such as syntactic, semantic and pragmatic ones.

Anúncio publicitário direcionado ao público masculino: uma abordagem dialógica

In this study, we intend to focus on the printed advertisement genre which reveals its discursive genre condition circulating in printed media sphere, specifically in four magazines: Playboy, Score, GQ and Men's Health. The overall objective of this study is to analyze the identity in advertisement gender directed at male audience in printing, by considering how commercials work in the consumer society by seeking to satisfy a particular group, the reader/male consumer with modern customs and behaviors. For this, advertisements from four magazines of January, April, July and October were gathered, totaling sixteen magazines and twenty-seven types of genre pieces over a period of one year: from January to December 2012. We have selected about 27 pieces that advertisers tried to expose the body on the space of advertisements, resulting in a heightened appreciation of physical appearance. So we divide our corpus in a category, adiáforo body, and three sub-categories: the body building; the tattooed body and the consumption body. This work is part of a qualitative-interpretative approach, in order to investigate the social reality, paradigm advocated by applied linguists. Thus, our study is turned to a related activity with language issues present in the printed media sphere. Advertisement is understood as real unity of discursive and inter-subjective communication, maintaining relationships with others statements already said and prefigured and calling others to settle. Based on these assumptions, we have presented an analysis of the printed advertisement gender in men's magazines basing ourselves in contemporary research on Discourse Dialogic Analysis in Circle studies by Mikhail Bakhtin, revisiting his theoretical and methodological aspects and the identity concepts and culture as well as authors of the advertising sphere. This research has been presented relevant as it has contributed to an analysis of the verbal-visual dimension of advertising directed at male audience, considered as a discursive genre that circulates in the printed media and advertising, steeped in dialogical relations and have also contributed to the construction and development of theoretical and methodological frameworks, and applied to teachers and professionals interested in the theme. Results have shown data demonstrating that the search for a completeness never come, the man have built himself the search of the perfect body, the pursuit of exquisite stereotype, the search for products that contribute to this his self-assertion always transient and in construction. It is concluded that the body is a recurring theme in the four magazines. The body tailored is always presented as the ideal to which every man must achieve.

O direito penal do inimigo na atualidade: Mutual Legal Assistance Treaty – MLAT, em matéria penal, celebrado entre a República Federativa do Brasil e os Estados Unidos da América bem como seus reflexos na jurisdição brasileira

In view of the climate of instability and deep social inequalities, it has been evident in the Brazilian reality, a new way to punish systematic already developed and consolidated in other countries, in which, among other things, the criminality is anticipated only by danger that the individual sports. It appears, therefore, that the theory developed by Günter Jakobs, nominated Criminal Law of the Enemy, became subtly inserted in the Brazilian reality as well as in international relations signed. In this sense, the Brazilian State, in order to carry out the international legal cooperation in the criminal field, signed a mutual assistance agreement with the government of the United States of America. Forward the conclusion of Mutual legal Assistance Treaty (MLAT), the signatory countries voiced a desire to cooperate in order to facilitate the implementation of tasks of the authorities responsible for law enforcement in both countries, comprising research, investigation, prosecution and prevention of crime, said internalized adjustment in the Brazilian legal system by means of Decree No. 3810 of 02 May 2001. Alongside these considerations, the present study aims to analyze the Criminal law of the Enemy today, seeking to find evidence of that theory in the MLAT, international legal cooperation instrument signed between the government of the Federative Republic of Brazil and the government of the United States of America. Moreover, it has the objective to describe its effects on the Brazilian jurisdiction, especially as concerns the relativity and the suppression of human rights. Once done the introit, analysis will be carried out in the first chapter, on the definition and main features of the theory of Criminal Enemy of the law, it is imperative to approach the humanistic aspect that preceded the theory as well as the dealings given to some controversial issues surrounding it, such as the anticipation of the enemy's punishment and the disproportionality of the penalties imposed. In the second chapter will present the conceptual assumptions, historical evolution and the positives aspects, as well as the barriers and the pursuit of effectiveness of international legal cooperation. In the chapter, bedroom effective analysis of specific modality of cooperation will be held, the Mutual legal Assistance Treaty - MLAT in criminal matters, signed between the Federative Republic of Brazil and the United States of America, in which the general aspects will be addressed and the MLAT reflections on the Brazilian jurisdiction, which includes analysis about the relativity or suppression of human rights, future trends and creating stricter laws, followed by the presentation of the seized conclusion on the subject, in which, among other approaches, will be voiced understanding about the unconstitutionality certain service requests that, from these, there is the bad use of the agreed instrument.

Processos de imitação-criação como constituidores da práxis pedagógica: uma intervenção didático-formativa com o formador de professores

The research deals with the constitution of the pedagogical praxis of a teacher trainer, understood as objectification of theoretical and practical unity in the teaching field. It was achieved by means of a didactic-training intervention. The research problem: as a teacher trainer in a continuous training process is a pedagogical praxis, outlined to the overall objective: investigate the establishment of the pedagogical praxis of teacher trainer in a continuous formation process. The specific objectives were: 1) outline principles and foundations theoretical-methodological course of intervention research on appropriate teaching assumptions of historical-cultural theory; 2) systematic principles of constitution of the pedagogical praxis of a teacher trainer and 3) synthesize foundations of continued training of teacher trainers in view of the historical-cultural theory, to collaborate with design of institutional policies for continuing training of university teachers. The research was developed at the Federal University of Triângulo Mineiro University - UFTM, with teachers who work in their degree courses. It was developed in three stages: diagnosis, didactic-formative intervention and analysis of data. In the diagnostic step attended five teacher educators of degrees in: history, geography, physics, chemistry and letters. At this stage were used identification questionnaires, interviews, classroom observation and document analysis. In the next stage, with participation of a trainer, it was held educational-training intervention understood as the collective research-training process that is involved intervening in teaching with the development of interdependent and simultaneous actions trainings, planning and implementation of educational activities and study, classroom observation and evaluation from the perspective of dialectical unity in order to contribute to the integral development of teachers and students. The intervention were also held interviews and document analysis. The last stage of the research was the analysis of the data. In the diagnosis of education, among other analyzes, three references were found of the trainer's training-action: memorized references, empirical and praxis. It was the analysis of the references of the trainer's training-action that guided referrals ways of teaching-training intervention. As a result, it was concluded that the teacher educator is their pedagogical praxis in the dialectical units theoretical and practical appropriation of concepts and imitation-creation. Were the two principles analyzed in the research. It was also systematized some essential elements of the formation of the teacher educator: the needs of trainers are decisive in the choice of concepts that will be appropriate; the organization of the training process should take place hand in hand with planning and development classes; the theory need to be experienced in training so that appropriation/objectification of education come true, and also, participants must be strengthened as a collective studies, since we have not learned by linearity but connections. It is hoped that the research will create opportunities to deepen the debate on the continuing education of teacher educators and contribute to scientific production in the area.

RELIGIÃO, COLONIALISMO E ALTERIDADE EM ROGER WILLIAMS

Esta dissertação de mestrado apresenta os resultados da pesquisa sobre Roger Williams – pastor puritano, de origem inglesa, que migrou para a América a fim de participar da constituição da colônia de Massachusetts, no ano de 1631. Pergunta-se, nesta pesquisa, sobre os motivos que levaram Roger Williams a questionar o pensamento dominante, relativo à natureza do ameríndio e à legitimidade da ocupação de suas terras. Parte-se da tese de que a partir das experiências de Roger Williams, primeiro, com o sofrimento dos pobres e com perseguição religiosa na Inglaterra, segundo, suas próprias experiências na América, ele pôde contemplar os ameríndios como vítimas do sistema colonial inglês-puritano. Seu posicionamento seria, portanto, uma abertura à alteridade desses povos. Com isso, o objetivo determinado foi o de analisar a crítica de Roger Williams ao colonialismo inglês e sua defesa aos ameríndios, buscando compreendê-lo frente à alteridade dos ameríndios. Trata-se de uma bibliográfica das obras do autor e também de outros autores que tratam do tema. Como referência teórica, remetemo-nos ao pensamento de Enrique Dussel, principalmente, por meio de algumas categorias da Filosofia da Libertação, como Totalidade, Exterioridade, Alteridade, Alienação, Dominação e Libertação, que possibilitaram pensar o sistema colonial em sua incapacidade de contemplar a exterioridade ameríndia. Também, de Dussel, aplicou-se a reflexão sobre a crítica ética desde a negatividade das vítimas, para poder-se analisar o comportamento do personagem diante da violência colonial. E para a discussão sobre a sujeiticidade de Roger Williams, buscou-se o aporte de Franz J. Hinkelammert quanto à teoria do sujeito. Como resultado, os três capítulos da dissertação apresentam, respectivamente, uma síntese biográfica e contextual do personagem, seguida por uma exposição do debate sobre a humanidade e a civilidade dos ameríndios e sobre a questão da terra e, no terceiro capítulo, uma discussão sobre Roger Williams e a alteridade. Detectou-se, na trajetória do personagem, uma sensibilidade ética que o conduziu à defesa de grupos marginalizados socialmente, primeiro na Inglaterra e depois nas colônias. E diante disso, concluiu-se que a defesa dos ameríndios seguiu esse mesmo critério, possibilitando a Williams distanciar-se das pressuposições europeias quanto à sua superioridade para buscar novos paradigmas que orientassem as relações entre colonos e nativos. Espera-se que este trabalho possa contribuir para as reflexões críticas sobre a gênese do colonialismo e sobre os primeiros sinais de um pensamento crítico no interior do sistema colonial.

The role of parametric assumptions in adaptive Bayesian estimation.

Variants of adaptive Bayesian procedures for estimating the 5% point on a psychometric function were studied by simulation. Bias and standard error were the criteria to evaluate performance. The results indicated a superiority of (a) uniform priors, (b) model likelihood functions that are odd symmetric about threshold and that have parameter values larger than their counterparts in the psychometric function, (c) stimulus placement at the prior mean, and (d) estimates defined as the posterior mean. Unbiasedness arises in only 10 trials, and 20 trials ensure constant standard errors. The standard error of the estimates equals 0.617 times the inverse of the square root of the number of trials. Other variants yielded bias and larger standard errors.

Structural damage estimation using dynamic data and multi-objective optimization

Peer reviewed

Contradições como força de mudança: o processo de formação continuada de professores do ensino médio enquanto potencializador da práxis transformadora à luz da teoria histórico-cultural

The intervention research proposed was based on the Cultural-Historical Theory based on the laws and logic of materialism historical-dialectical. Therefore, we tried to design a research process that involved all as responsible for the process. In the field of continuous teacher's training usually has been found dualistic relationship / paradoxical processes as a result of the adopted training models which are characterized by individualist human processes. The teacher training work sought to overcome this dualism, to promote the unveiling of the contradictions with regard to teaching models. As a hypothesis, we imagined that immersed in this process, teachers recognize such contradictions, and this recognition would make the contradictions become the driving force of change in teaching practice, realizing the teaching-learning-development triad as the basis of praxis. Aiming to develop a process of continuing education to bring results to the professional teachers development looking for answer the following research question: How and what the changes of teachers who participated in the Didactic-Formative Intervention process raised the quality of their teaching practices? In this context, the objective of the research was to develop a process of Didactic-Formative Intervention from the perspective of Cultural-Historical Theory with high school teachers in order to theorize about the changes in pedagogical practices of teachers and learn aspects that transform the essence teaching practice. The research involved two high school teachers of a public school in Uberlândia-MG. The training meetings took place at the school through a collective study group between the years 2013 and 2015. As procedures were used two interconnected aspects: classes observations, and a theoretical and methodological training, both for diagnosis and for the process evaluation, the second aspect has a formative dimension, and a didactic dimension (double meaning) to form didactically the teacher and to elaborate didactic procedures. The collected data were analyzed by observing the assumptions of the method, analysis by units and the processuality. As results teachers showed changes in their teaching practices regarding the organization of the pedagogical work and also centered their design educational actions based on learning and development of the students. The presence of continuous diagnosis during the classes, work with a systems of concepts and their conceptual links, problematization as a teaching method can be pointed as meaningful changes in their praxis. Regarding the training activities that emerged from the analysis of the compiled materials and analyzed throughout the process can be emphasized: forming a collective group of school teachers continuous training, diagnostics, development of practical activities, increase relationships among participants, the choice of scientific material used should have direct relation to the needs of the participants, promoting conditions that enable the emergence of contradictions between the pedagogical practice of teachers and teaching based on the perspective of the Cultural-Historical Theory. This research craved to develop and design a teachers' training processes that increase the quality of teachers life and ways of teaching in the Brazilian public school.

On Provable Algorithms for Determination of Continuous Protein Interdomain Motions from Residual Dipolar Couplings

Dynamics of biomolecules over various spatial and time scales are essential for biological functions such as molecular recognition, catalysis and signaling. However, reconstruction of biomolecular dynamics from experimental observables requires the determination of a conformational probability distribution. Unfortunately, these distributions cannot be fully constrained by the limited information from experiments, making the problem an ill-posed one in the terminology of Hadamard. The ill-posed nature of the problem comes from the fact that it has no unique solution. Multiple or even an infinite number of solutions may exist. To avoid the ill-posed nature, the problem needs to be regularized by making assumptions, which inevitably introduce biases into the result.

Here, I present two continuous probability density function approaches to solve an important inverse problem called the RDC trigonometric moment problem. By focusing on interdomain orientations we reduced the problem to determination of a distribution on the 3D rotational space from residual dipolar couplings (RDCs). We derived an analytical equation that relates alignment tensors of adjacent domains, which serves as the foundation of the two methods. In the first approach, the ill-posed nature of the problem was avoided by introducing a continuous distribution model, which enjoys a smoothness assumption. To find the optimal solution for the distribution, we also designed an efficient branch-and-bound algorithm that exploits the mathematical structure of the analytical solutions. The algorithm is guaranteed to find the distribution that best satisfies the analytical relationship. We observed good performance of the method when tested under various levels of experimental noise and when applied to two protein systems. The second approach avoids the use of any model by employing maximum entropy principles. This 'model-free' approach delivers the least biased result which presents our state of knowledge. In this approach, the solution is an exponential function of Lagrange multipliers. To determine the multipliers, a convex objective function is constructed. Consequently, the maximum entropy solution can be found easily by gradient descent methods. Both algorithms can be applied to biomolecular RDC data in general, including data from RNA and DNA molecules.

Cervical cancer precursors and hormonal contraceptive use in HIV-positive women: application of a causal model and semi-parametric estimation methods.

OBJECTIVE: To demonstrate the application of causal inference methods to observational data in the obstetrics and gynecology field, particularly causal modeling and semi-parametric estimation. BACKGROUND: Human immunodeficiency virus (HIV)-positive women are at increased risk for cervical cancer and its treatable precursors. Determining whether potential risk factors such as hormonal contraception are true causes is critical for informing public health strategies as longevity increases among HIV-positive women in developing countries. METHODS: We developed a causal model of the factors related to combined oral contraceptive (COC) use and cervical intraepithelial neoplasia 2 or greater (CIN2+) and modified the model to fit the observed data, drawn from women in a cervical cancer screening program at HIV clinics in Kenya. Assumptions required for substantiation of a causal relationship were assessed. We estimated the population-level association using semi-parametric methods: g-computation, inverse probability of treatment weighting, and targeted maximum likelihood estimation. RESULTS: We identified 2 plausible causal paths from COC use to CIN2+: via HPV infection and via increased disease progression. Study data enabled estimation of the latter only with strong assumptions of no unmeasured confounding. Of 2,519 women under 50 screened per protocol, 219 (8.7%) were diagnosed with CIN2+. Marginal modeling suggested a 2.9% (95% confidence interval 0.1%, 6.9%) increase in prevalence of CIN2+ if all women under 50 were exposed to COC; the significance of this association was sensitive to method of estimation and exposure misclassification. CONCLUSION: Use of causal modeling enabled clear representation of the causal relationship of interest and the assumptions required to estimate that relationship from the observed data. Semi-parametric estimation methods provided flexibility and reduced reliance on correct model form. Although selected results suggest an increased prevalence of CIN2+ associated with COC, evidence is insufficient to conclude causality. Priority areas for future studies to better satisfy causal criteria are identified.