O objetivo deste trabalho é apresentar uma metodologia de cálculo da distribuição de correntes e dos campos eletromagnéticos e tensões induzidas associadas em estruturas atingidas diretamente por descargas atmosféricas que, agregada à filosofia geral de compatibilidade eletromagnética (CEM), constitua uma abordagem inovadora e abrangente quando comparada às recomendações de proteção contra descargas atmosféricas atuais. Propõe-se, portanto, desenvolver uma metodologia que: · Constitua uma ferramenta de auxílio nas tomadas de decisões, aplicável desde a etapa de definição da arquitetura da estrutura e do leiaute dos equipamentos até a definição final da configuração do sistema de proteção contra descargas atmosféricas (S.P.C.D.A); · Possibilite a implementação de uma filosofia de proteção dos equipamentos e sistemas elétricos e eletrônicos contra descargas atmosféricas na qual se integre as recomendações tradicionais às necessidades atuais relacionadas à área de compatibilidade eletromagnética; · Seja abrangente e com grau de precisão satisfatório, quando comparadas com as recomendações atuais, com possibilidade de exploração dos valores das grandezas elétricas envolvidas no domínio do espaço e do tempo, e · Apresente simplicidade na implementação em computadores pessoais. / The main purpose of this work is to present a suitable method for calculating the current distribution, the electric and magnetic field, and the induced voltage on electric circuits regarding a structure directly struck by lightning. Moreover, when the method is used together with the electromagnetic compatibility (EMC) requirements, it can provide the designer with a new and helpful methodology meeting the recent aspects or the state of the art on lightning protection systems (L.P.S). Thus, a methodology is proposed, which provides the L.P.S. design team with: · The availability to take technical decisions in all steps of the project, from the definition of the architecture of the structure to the definition of the best layout of L.P.S.; · Recommendations to achieve the EMC of the electric and electronic system, in addition to the traditional ones; · Reliable numerical results concerning simulations in the space and time-domain, and · Simple implementation in personal computers.

O objetivo deste trabalho é apresentar uma metodologia de cálculo da distribuição de correntes e dos campos eletromagnéticos e tensões induzidas associadas em estruturas atingidas diretamente por descargas atmosféricas que, agregada à filosofia geral de compatibilidade eletromagnética (CEM), constitua uma abordagem inovadora e abrangente quando comparada às recomendações de proteção contra descargas atmosféricas atuais. Propõe-se, portanto, desenvolver uma metodologia que: · Constitua uma ferramenta de auxílio nas tomadas de decisões, aplicável desde a etapa de definição da arquitetura da estrutura e do leiaute dos equipamentos até a definição final da configuração do sistema de proteção contra descargas atmosféricas (S.P.C.D.A); · Possibilite a implementação de uma filosofia de proteção dos equipamentos e sistemas elétricos e eletrônicos contra descargas atmosféricas na qual se integre as recomendações tradicionais às necessidades atuais relacionadas à área de compatibilidade eletromagnética; · Seja abrangente e com grau de precisão satisfatório, quando comparadas com as recomendações atuais, com possibilidade de exploração dos valores das grandezas elétricas envolvidas no domínio do espaço e do tempo, e · Apresente simplicidade na implementação em computadores pessoais. / The main purpose of this work is to present a suitable method for calculating the current distribution, the electric and magnetic field, and the induced voltage on electric circuits regarding a structure directly struck by lightning. Moreover, when the method is used together with the electromagnetic compatibility (EMC) requirements, it can provide the designer with a new and helpful methodology meeting the recent aspects or the state of the art on lightning protection systems (L.P.S). Thus, a methodology is proposed, which provides the L.P.S. design team with: · The availability to take technical decisions in all steps of the project, from the definition of the architecture of the structure to the definition of the best layout of L.P.S.; · Recommendations to achieve the EMC of the electric and electronic system, in addition to the traditional ones; · Reliable numerical results concerning simulations in the space and time-domain, and · Simple implementation in personal computers.

Ethanol from lignocellulosic biomass is a promising alternative to rapidly depleting oil reserves. However, natural recalcitrance of lignocelluloses to biological and chemical treatments presents major engineering challenges in designing an ethanol conversion process. Current methods for pretreatment and hydrolysis of lignocelluloses generate a mixture of pentose (C5) and hexose (C6) sugars, and several microbial growth inhibitors such as acetic acid and phenolic compounds. Hence, an efficient ethanol production process requires a fermenting microorganism not only capable of converting mixed sugars to ethanol with high yield and productivity, but also having high tolerance to inhibitors. Although recombinant bacteria and yeast strains have been developed, ethanol yield and productivity from C5 sugars in the presence of inhibitors remain low and need to be further improved for a commercial ethanol production. The overarching objective of this work is to transform Zymomonas mobilis into an efficient whole-cell biocatalyst for ethanol production from lignocelluloses. Z. mobilis, a natural ethanologen, is ideal for this application but xylose (a C5 sugar) is not its 'natural' substrate. Back in 1995, researches at National Renewable Energy Laboratory (NREL) had managed to overcome this obstacle by metabolically engineering Z. mobilis to utilize xylose. However, even after more than a decade of research, xylose fermentation by Z. mobilis is still inefficient compared to that of glucose. For example, volumetric productivity of ethanol from xylose fermentation is 3- to 4- fold lower than that from glucose fermentation. Further reduction or complete inhibition of xylose fermentation occurs under adverse conditions. Also, high concentrations of xylose do not get metabolized completely. Thus, improvement in xylose fermentation by Z. mobilis is required. In this work, xylose fermentation in a metabolically engineered Z. mobilis was markedly improved by applying the technique of adaptive mutation. The adapted strain was able to grow on 10% (w/v) xylose and rapidly ferment xylose to ethanol within 2 days and retained high ethanol yield. Similarly, in mixed glucose-xylose fermentation, the strain produced a total of 9% (w/v) ethanol from two doses of 5% glucose and 5% xylose (or a total of 10% glucose and 10% xylose). Investigation was done to identify the molecular basis for efficient biocatalysis. An altered xylitol metabolism with reduced xylitol formation, increased xylitol tolerance and higher xylose isomerase activity were found to contribute towards improvement in xylose fermentation. Lower xylitol production in adapted strain was due to a single mutation in ZMO0976 gene, which drastically lowered the reductase activity of ZMO0976 protein. ZMO0976 was characterized as a novel aldo-keto reductase capable of reducing xylose, xylulose, benzaldehyde, furfural, 5-hydroxymethyl furfural, and acetaldehyde, but not glucose or fructose. It exhibited nearly 150-times higher affinity with benzaldehyde than xylose. Knockout of ZMO0976 was found to facilitate the establishment of xylose fermentation in Z. mobilis ZM4. Equipped with molecular level understanding of the biocatalytic process and insight into Z. mobilis central carbon metabolism, further genetic engineering of Z. mobilis was undertaken to improve the fermentation of sugars and lignocellulosic hydrolysates. These efforts culminated in construction of a strain capable of fermenting glucose-xylose mixture in presence of high concentration of acetic acid and another strain with a partially operational EMP pathway.

No description available.

Submitted by Caroline Xavier (caroline.xavier@pucrs.br) on 2017-06-30T18:19:05Z No. of bitstreams: 1 DIS_GREICE_DE_CARLI_ROMAN_COMPLETO.pdf: 9835425 bytes, checksum: aa605361de91b916006af4710a54365b (MD5) / Made available in DSpace on 2017-06-30T18:19:05Z (GMT). No. of bitstreams: 1 DIS_GREICE_DE_CARLI_ROMAN_COMPLETO.pdf: 9835425 bytes, checksum: aa605361de91b916006af4710a54365b (MD5) Previous issue date: 2016-12-15 / Em fevereiro de 2001, o Manifesto ?gil foi proposto tendo como princ?pio equipes pequenas e co-localizadas. No entanto, ao longo destes 16 anos, a agilidade tamb?m foi posta em pr?tica em outros contextos, como por exemplo: equipes distribu?das e sistemas complexos, utilizando-se o termo "Desenvolvimento ?gil em Larga Escala". N?o h? uma defini??o clara e compreensiva de como a agilidade est? presente neste contexto. Assim, nosso trabalho preenche essa lacuna com o objetivo de caracterizar a agilidade no Desenvolvimento ?gil em Larga Escala. Neste trabalho, realizou-se um estudo organizado em duas fases. Na Fase 1, denominada Base Te?rica, realizamos um estudo do estado-da-arte da ?rea. Na Fase 2, denominado Estudo Emp?rico, n?s realizamos duas investiga??es: um estudo de campo em uma empresa ?gil em larga escala, para identificar o desenvolvimento durante o processo de transforma??o da empresa para esta nova abordagem e, um grupo focal, para identificar como as equipes ?geis em larga escala que v?m utilizando os m?todos ?geis o quanto se percebem em termos de aspectos de maturidade ?gil. Estes resultados contribuem para os pesquisadores e profissionais entenderem melhor como a agilidade e definida e percebida nestes grandes ambientes. O conhecimento e ?til para aqueles que querem entender como o desenvolvimento ?gil se adapta a tais ambientes e para pesquisadores com o objetivo de se aprofundar sobre o tema. / The Agile Manifesto was proposed in February 2001 having in mind small and collocated teams. However, agile has also been put in practice in other settings (e.g. large teams, distributed teams, complex systems) under the term ?Large-Scale Agile Development' (LSAD). There is no clear definition for and understanding of how agility is present in this setting. Thus, our work fills in this gap aiming to characterize agility in LSAD. We conducted a study organized in two phases. In Phase 1, named Theoretical Base, we conducted the state-of-the-art of the area. In Phase 2, named Empirical Study, we conducted two investigations: a field study in a large-scale agile company to identify how agility was developed during the transformation process of the company to this new approach, and a focus group to identify how large-scale agile teams that have been using agile for a certain while perceive themselves in terms of maturity in agile aspects. Findings contribute to researchers and professionals better understand how agility is defined and perceived in large settings. This knowledge is useful for those who want to enter the agile journey in such similar environments and for researchers aiming to further explore the topic.

Submitted by PPG Ci?ncia da Computa??o (ppgcc@pucrs.br) on 2018-07-16T17:26:53Z No. of bitstreams: 1 ELISA COSTA DIEL_DIS.pdf: 2030569 bytes, checksum: 97dac6ad532e10d4b88caec8f69d282e (MD5) / Approved for entry into archive by Sheila Dias (sheila.dias@pucrs.br) on 2018-07-23T11:12:32Z (GMT) No. of bitstreams: 1 ELISA COSTA DIEL_DIS.pdf: 2030569 bytes, checksum: 97dac6ad532e10d4b88caec8f69d282e (MD5) / Made available in DSpace on 2018-07-23T11:31:48Z (GMT). No. of bitstreams: 1 ELISA COSTA DIEL_DIS.pdf: 2030569 bytes, checksum: 97dac6ad532e10d4b88caec8f69d282e (MD5) Previous issue date: 2017-03-16 / Apesar de o ?gil buscar colabora??o com todos as partes envolvidas, a maioria dos projetos ?geis n?o extende essa colabora??o para o pessoal de opera??es. Problemas de comunica??o s?o um problema recorrente em equipes ?geis que tamb?m ? eminente na rela??o entre desenvolvedores e opera??es. Esta pesquisa visa compreender como a comunica??o acontece em DevOps a partir das percep??es dos praticantes. Para alcan?ar nosso objetivo, realizou-se uma Revis?o de Literatura sobre DevOps e Comunica??o, e conduziu-se um Estudo de Campo com dados qualitativos sendo coletados atrav?s de entrevistas. Os resultados indicam que hoje existem pelo menos tr?s configura??es diferentes de DevOps sendo aplicadas na ind?stria: profissionais Devs e Ops alocados na mesma equipe; uma equipe de DevOps com um conjunto de habilidades compartilhadas; e uma equipe separada de Dev e Ops trabalhando juntos. Apesar dessas configura??es, n?o foram encontradas nenhuma particularidade. Em resumo, os resultados indicam que os membros de equipes co-alocadas e multi-funcionais se comunicam melhor; ? importante trabalhar em conjunto e compartilhar conhecimentos t?cnicos; o poder de decis?o variar? de acordo com a situa??o enfrentada; entre outros. Nossas descobertas ajudam a diminuir a lacuna apontada por Erich, Amrit e Daneva entre Dev e Ops, avan?ando para uma melhor compreens?o de como profissionais DevOps colaboram, ajudando eles a melhorar suas pr?ticas de comunica??o em seu trabalho di?rio. / Even though agile actively seeks collaboration with all kinds of stakeholders, most agile projects do not extend toward the operations people. Issues in communication are a recurring issue in agile teams. Such issues are also eminent in the relationship between developers and operations. This study aims to understand how communication happens in DevOps from the perspective of practitioners. To achieve our goal, a Literature Review on DevOps and Communication was performed, and a Field Study was conducted with qualitative data being collected through interviews. Results revealed that today there are at least three different DevOps configurations being applied in the industry, being: Dev and Ops professionals allocated to the same team; a team of DevOps with a shared skill set; and a separate team of Dev and Ops working together. Despite the configurations, we did not find any particularities. In summary, results show that co-allocated and cross functional team members communicate better; it is important to work together as a single team and share technical knowledge; decision power changes based on the situation that is being faced; among others. Our findings help to narrow the gap pointed out by Erich, Amrit, and Daneva between Dev and Ops, moving towards a better understanding of how DevOps team collaborates by helping practitioners to improve their communication practices in their daily work.

Submitted by PPG Ci?ncia da Computa??o (ppgcc@pucrs.br) on 2018-10-09T13:24:12Z No. of bitstreams: 1 LUIS FERNANDES VAZ.DIS.pdf: 17076970 bytes, checksum: 6f8adcfdc62d9c6204d43c0aaaace7e5 (MD5) / Approved for entry into archive by Caroline Xavier (caroline.xavier@pucrs.br) on 2018-10-09T17:12:07Z (GMT) No. of bitstreams: 1 LUIS FERNANDES VAZ.DIS.pdf: 17076970 bytes, checksum: 6f8adcfdc62d9c6204d43c0aaaace7e5 (MD5) / Made available in DSpace on 2018-10-09T17:16:23Z (GMT). No. of bitstreams: 1 LUIS FERNANDES VAZ.DIS.pdf: 17076970 bytes, checksum: 6f8adcfdc62d9c6204d43c0aaaace7e5 (MD5) Previous issue date: 2018-03-27 / This research aimed to investigate task documentation in Software Crowdsourcing, more specifically, in the TopCoder platform. It also aimed to identify the elements that should be considered in the documentation of a task in this kind of software development. This research is of importance when considering that a Task is the component that links the other components of the software crowdsourcing model, which are: the Buyer, the Platform, and the Crowd. It is the task that expresses the Buyer?s need to the crowd members. We followed a qualitative research approach and conducted a Case Study with newcomers in Software Crowdsourcing and a Field Study with industry professionals. Data was analyzed using the Content Analysis technique. We found that, for the Case Study novices, the documentation of the task had a secondary role in the task selection. However, the need of a clear documentation become more relevant during the development of the task given that this is the moment that the instructions within the documentation need to be decoded by the developer and turned into a solution to be later submitted to the platform. For the Field Study participants, the most relevant elements related to the documentation of a task were how clear the description of a task is and their prior knowledge about the task content in order to influence its selection. Inspired on our studies? results, we propose a model for task documentation in TopCoder. We believe this model will likely aid the description of tasks in software crowdsourcing and will, as a consequence, help crowd members in their task development journey. / A presente pesquisa teve como objetivo investigar a documenta??o das tarefas disponibilizadas na plataforma TopCoder e os elementos que devem ser considerados na documenta??o de uma tarefa em Software Crowdsourcing. Esta investiga??o torna-se relevante na medida em que a Tarefa ? o elemento fundamental de liga??o entre os demais elementos do modelo de Software Crowdsourcing (Contratante, Plataforma e Multid?o). ? a Tarefa que expressa a necessidade do Contratante para os membros da multid?o. Assim, para o desenvolvimento desta investiga??o foi adotada a abordagem qualitativa, por meio de um Estudo de Caso com novatos em Software Crowdsourcing e de um Estudo de Campo, com profissionais da ind?stria. Para a an?lise e interpreta??o dos dados foi aplicada a t?cnica de An?lise de Conte?do. Como resultado desta pesquisa, constatou-se que no Estudo de Caso a documenta??o da tarefa teve um papel secund?rio quando os participantes selecionavam as tarefas. Entretanto, o papel da clareza da documenta??o surge com maior for?a durante a execu??o da tarefa, uma vez que ? neste momento que deve ser decodificada a instru??o da documenta??o a fim de realizar efetivamente a tarefa e submet?-la ? plataforma. Para os participantes do Estudo de Campo, os elementos mais relevantes referentes ? documenta??o das tarefas foram a clareza na descri??o da tarefa e o conhecimento sobre o assunto tratado pela tarefa. A partir dos resultados obtidos ? proposto um modelo de documenta??o de tarefa a ser utilizado na plataforma TopCoder. Acredita-se que com o mapeamento dos elementos identificados na pesquisa e a proposta de um modelo de documenta??o para a tarefa ser? poss?vel aprimorar a descri??o das tarefas e consequentemente as entregas realizadas pelos membros da multid?o.

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2017-09-12T18:24:02Z No. of bitstreams: 1 2016 - Larissa Henriques Evangelista Castro.pdf: 3738174 bytes, checksum: 04e651a55fa9b4054c2810389592be67 (MD5) / Made available in DSpace on 2017-09-12T18:24:02Z (GMT). No. of bitstreams: 1 2016 - Larissa Henriques Evangelista Castro.pdf: 3738174 bytes, checksum: 04e651a55fa9b4054c2810389592be67 (MD5) Previous issue date: 2016-12-02 / CAPES / CNPq / FAPERJ / Trypanosoma cruzi is the parasite that causes american trypanosomiasis (or Chagas disease), a neglected tropical disease previously restricted to South and Central Americas and Mexico, but now with several cases around the world. Currently in Brazil, the treatment of Chagas disease is done, only using benznidazole, which is not effective for the disease?s chronic phase and causes aggressive side effects, which explains the necessity of researches to find novel anti-Chagas compounds. A strategy adopted for the development of bioactive compounds against T. cruzi consists on the inhibition of the sterol 14?-demethylase enzyme (CYP51), which is essential for the parasite?s cellular membrane integrity. The inhibition can be achieved by a complexation of heterocyclic ring-containing compounds with the iron atom of heme group, present on CYP51. Thus, molecular modeling techniques were used on this study to analyze the interaction of a heterocyclic compounds (with known activity) with T. cruzi CYP51 in order to obtain the necessary information to construct an effective model for the theoretical activity prediction of these and also novel compounds. The proposed model presented a good multiple correlation coefficient (r? = 0.84) with the terms used to its construction. The model was used to help the design of novel piperine derivatives with a triazole ring, that presented promising theorical activities against T. cruzi CYP51, calculated by the model. The most promising compounds were selected and synthesized with the purpose of being tested in vitro and in vivo against T. cruzi. / O Trypanosoma cruzi ? o parasito causador da tripanossom?ase americana (Doen?a de Chagas), uma doen?a tropical negligenciada antes restrita ? Am?rica do Sul, Am?rica Central e M?xico, mas que vem apresentando um n?mero cada vez maior de casos no mundo. Atualmente, o tratamento da Doen?a de Chagas no Brasil ? limitado ao uso do f?rmaco benzonidazol, que ? pouco eficaz para a fase cr?nica da doen?a e causa efeitos colaterais agressivos, o que torna a pesquisa por novos f?rmacos imprescind?vel. Uma estrat?gia adotada para o desenvolvimento de compostos bioativos contra T. cruzi consiste na inibi??o de uma enzima essencial para a integridade da membrana celular do parasito, a enzima esterol 14?-desmetilase (CYP51), causada pela coordena??o de compostos contendo an?is heteroc?clicos com o ?tomo de ferro do grupo heme presente na enzima, fundamental para a atividade. Dessa maneira, foram utilizadas nesse estudo t?cnicas de modelagem molecular, incluindo docagem molecular e c?lculos qu?nticos semi-emp?ricos, para analisar a intera??o de uma s?rie de compostos heteroc?clicos de atividade conhecida sobre a CYP51 do T. cruzi e com isso se obter informa??es necess?rias para a constru??o de um modelo efetivo para a previs?o te?rica da atividade destes compostos. O modelo proposto apresentou um bom coeficiente de correla??o m?ltipla com os termos utilizados para sua constru??o, com um r?=0,84. Esse modelo foi utilizado para o planejamento de novos triaz?is derivados da piperina, com atividade te?rica calculada promissora contra a CYP51 de T. cruzi. Alguns dos melhores compostos foram selecionados e sintetizados neste projeto, com a proposta de serem avaliados em testes in vitro e in vivo contra a doen?a de Chagas.

Made available in DSpace on 2014-12-17T15:53:12Z (GMT). No. of bitstreams: 1 JoaoMariaMR.pdf: 348399 bytes, checksum: fa0b19b3fa026bdbff4a3c9463313a2d (MD5) Previous issue date: 2006-05-19 / The purpose of this paper is to identify how real estate companies from the city of Natal measure their organizational performance. Traditionally these companies measure their performance using financial measures; however, the technological improvement, the internationalization of the economy and the change in consumer behavior all demand better products and services, and other measuring models. Those changes motivate organizations to continually improve the quality of their products and services. In this way, these companies need to associate their financial results to their global performance. Therefore, it is necessary to have organizational performance models that associate financial and non-financial measures to the strategies of the companies. The research also tries to identify which performance indicators are used by these companies, as well as to test a model who questions: a) if there is any relationship between managers? characteristics and performance measuring systems? characteristics; b) if there is any relationship between the company s characteristics and the characteristics of the measuring system used to evaluate its organizational performance and c) finally to verify if there is a relationship between the characteristics of the measuring system and the company s performance. The information which served as a basis for the study was obtained through an empirical research, with questionnaires, answered by 66 (sixty six) companies from the city of Natal, capital of the state of Rio Grande do Norte. The results show that none of the companies investigated use any of the performance measurement models proposed in the modern literature. However, they use on an isolated way some of the measures those models, including some measures from adopted in the Balanced Scorecard, as well as the benchmarking process, making comparisons with the performance of their competitors. The research also reveals that either bigger companies, companies with more experienced managers or with better performance show better performance measurement systems / Objetiva identificar como as imobili?rias da cidade do Natal medem seu desempenho organizacional. Tradicionalmente, as empresas avaliam o desempenho de seus processos, basicamente, utilizando medidas financeiras; por?m, o avan?o tecnol?gico, a internacionaliza??o da economia e a mudan?a no comportamento do consumidor exigem produtos e servi?os cada vez melhores, al?m de outros conjuntos de medi??o. Tais modifica??es motivam as organiza??es ? cont?nua melhoria da qualidade de seus produtos e servi?os. Nesse sentido, as empresas precisam associar os seus resultados financeiros ao seu desempenho global, necessitando, portanto, de modelos de avalia??o de desempenho organizacional, que associem medidas financeiras e n?o-financeiras ? estrat?gia das empresas. A pesquisa tamb?m procura responder quais os indicadores de desempenho utilizados por essas empresas, bem como testar um modelo conceitual, que questiona: a) se existe rela??o entre as caracter?sticas dos gestores e as caracter?sticas dos sistemas de medi??o; b) se existe rela??o entre as caracter?sticas da empresa e as caracter?sticas do sistema de medi??o, utilizado para avaliar seu desempenho organizacional; e c) se existe rela??o entre as caracter?sticas dos sistemas de medi??o e o desempenho da empresa. As informa??es, tomadas como base para o estudo, foram obtidas por meio de uma pesquisa emp?rica, com question?rios, junto a 66 (sessenta e seis) empresas da cidade do Natal, capital do Estado do Rio Grande do Norte. Os resultados revelam que as empresas pesquisadas n?o utilizam nenhum dos sistemas de avalia??o de desempenho mais modernos, citados na literatura. Contudo, utilizam isoladamente algumas medidas desses modelos, entre as quais algumas adotadas no Balance Scorecard, bem como realizam o processo de benchmarking, por meio de compara??es com o desempenho de seus concorrentes. A pesquisa tamb?m revela que empresas que t?m seus gestores com mais experi?ncia, empresas maiores e com melhor desempenho apresentam sistemas de medi??o mais sofisticados

Made available in DSpace on 2014-12-17T14:08:40Z (GMT). No. of bitstreams: 1 FelipeZA_DISSERT.PDF: 5156580 bytes, checksum: cf88acbbf99c9d93a555a758d3e21bf5 (MD5) Previous issue date: 2010-10-23 / The seismic processing technique has the main objective to provide adequate picture of geological structures from subsurface of sedimentary basins. Among the key steps of this process is the enhancement of seismic reflections by filtering unwanted signals, called seismic noise, the improvement of signals of interest and the application of imaging procedures. The seismic noise may appear random or coherent. This dissertation will present a technique to attenuate coherent noise, such as ground roll and multiple reflections, based on Empirical Mode Decomposition method. This method will be applied to decompose the seismic trace into Intrinsic Mode Functions. These functions have the properties of being symmetric, with local mean equals zero and the same number of zero-crossing and extremes. The developed technique was tested on synthetic and real data, and the results were considered encouraging / O processamento s?smico tem como principal objetivo fornecer imagem adequada das estruturas geol?gicas da sub-superf?cie de bacias sedimentares. Dentre as etapas fundamentais deste processamento est? o enriquecimento das reflex?es s?smicas atrav?s de filtragem de sinais indesej?veis, chamados de ru?dos, a amplifica??o de sinais de interesse e a aplica??o de processos de imageamento. Os ru?dos s?smicos podem aparecer de forma aleat?ria ou coerente. Nesta disserta??o ser? apresentado uma t?cnica para atenuar ru?dos coerentes, como o ground roll e as reflex?es m?ltiplas, baseado na Decomposi??o em Modos Emp?ricos. Este m?todo consiste em decompor o tra?o s?smico em Fun??es de Modo Intr?nseco, que s?o fun??es sim?tricas com m?dia local igual a zero e mesmo n?mero de zeros e extremos. A t?cnica desenvolvida foi testado em dados sint?ticos e reais, e os resultados obtidos foram considerados encorajadores