Submitted by PPG Ci?ncia da Computa??o (ppgcc@pucrs.br) on 2018-05-28T12:31:15Z No. of bitstreams: 1 TABAJARA_KRAUSBURG_RODRIGUES_DIS.pdf: 4049392 bytes, checksum: 154302eff9df959cfa74d6c0faec5d4e (MD5) / Approved for entry into archive by Sheila Dias (sheila.dias@pucrs.br) on 2018-06-06T13:05:51Z (GMT) No. of bitstreams: 1 TABAJARA_KRAUSBURG_RODRIGUES_DIS.pdf: 4049392 bytes, checksum: 154302eff9df959cfa74d6c0faec5d4e (MD5) / Made available in DSpace on 2018-06-06T13:35:29Z (GMT). No. of bitstreams: 1 TABAJARA_KRAUSBURG_RODRIGUES_DIS.pdf: 4049392 bytes, checksum: 154302eff9df959cfa74d6c0faec5d4e (MD5) Previous issue date: 2018-03-26 / Esta disserta??o apresenta um estudo sobre forma??o de coaliz?es entre agentes heterog?neos para a competi??o de programa??o multiagente de 2017. Foi investigado e aplicado a forma??o de estruturas de coaliz?es entre agentes para resolver problemas log?sticos simulados sobre o mapa de uma cidade real. A fim de atingir o objetivo deste trabalho, foram integrados algoritmos formadores de coaliz?es na plataforma JaCaMo por meio de um artefato CArtAgO chamado CFArtefact. Foi utilizada a implementa??o provida pelo time SMART-JaCaMo (time participante da competi??o multiagente), para experimentar a forma??o de coaliz?es na competi??o. Tr?s abordagens foram avaliadas no dom?nio da competi??o em diferentes configura??es. A primeira abordagem utiliza somente aloca??o de tarefas para resolver o problema. A segunda e a terceira abordagem utilizam a t?cnica de forma??o de coaliz?es anteriormente ? aloca??o de tarefas; dentre estas abordagens, uma utiliza um algor?timo ?timo para resolver o problema e a outra um heur?stico. As an?lises dos experimentos realizados mostram que algor?timos formadores de coaliz?es podem melhorar a performance do time participante da competi??o quando a taxa de trabalhos gerados pelo simulador ? baixa. Entretanto, conforme a taxa de trabalhos aumenta, a abordagem que realiza somente aloca??o de tarefas obt?m um desempenho melhor quando comparada as demais. Mesmo a abordagem heur?stica tem desempenho pr?ximo ? abordagem ?tima para coaliz?es. Desta forma, ? poss?vel concluir que forma??o de coaliz?es possui grande valia para balancear os agentes para um conjunto de trabalhos que precisa ser completado. / This work focuses on coalition formation among heterogeneous agents for the 2017 multiagent programming contest. An agent is a computer system that is capable of independent action to achieve its goals. In order to increase the effectiveness of the agents, we can organise them into coalitions, in which the agents collaborate with each other to achieve individual or common goals. We investigate and apply coalition structure generation (the first activity of the coalition formation process) in simulated scenarios, specifically the 2017 contest scenario, where the agents forming a competing team cooperate to solve logistic problems simulated on the map of a real city. In order to achieve our goal, we integrate coalition formation algorithms into the JaCaMo platform by means of a CArtAgO artefact, named CFArtefact. We use the implementation of the SMART JaCaMo team for experimenting with the coalition formation approach in the contest scenario. We experiment on three approaches in the contest domain with different configurations. In the first, we use only a taskallocation mechanism, while the other approaches use an optimal coalition formation algorithm and a heuristic coalition formation algorithm. We conducted several experiments to compare the advantages of each approach. Our results show that coalition formation algorithms can improve the performance of a participating team when dealing with low job rates (i.e., how quickly new jobs are created by the simulation). However, as we increase the job rate, the approach using only task allocation has better performance. Even a heuristic coalition formation approach has close performance to the optimal one in that case. Coalition formation can play an important role when we aim to balance each group of agents to accomplish some particular goal given a larger team of cooperating agents.

Made available in DSpace on 2014-12-17T14:33:09Z (GMT). No. of bitstreams: 1 KarolLBOF_DISSERT_PARCIAL.pdf: 340660 bytes, checksum: f2a188d52831a6a40d06910a31049e94 (MD5) Previous issue date: 2012-07-05 / How ecologically similar species are able to coexist has always generated great interest in the scientific community. Classical niche theory predicts that species coexistence is only possible when they segregate in at least one dimension of the ecological niche, thus leading to ecological differentiation among species. However, recent work has shown that species that are more similar in some ecological traits are the ones more prone to be able to coexist (environmental filter). The knowledge of how these forces act shaping ecological communities can reveal co-existence strategies, providing important information for management and conservation of the species. This study tested these hypotheses using a pair of coexisting species of Herpsilochmus, H. pectoralis and H. sellowi. In this study I use high resolution (50 x 50 m) ecological niche models to Identify which environmental factors best predict species occurrence. Next, I calculate the overlap in habitat use by species and build null models to test the hypothesis of spatial niche segregation. In addition, I obtain the selectivity parameters of habitat use to test whether the species H. pectoralis (larger body size) is less selective than H. sellowi (smaller body size) as stated in the literature for other species. The results reject the ecological equivalence among species, revealing that the species of Herpsilochmus explore the habitat differently, having different environmental niches. The hypothesis of environmental filter was not observed in my analysis, the observed overlap in habitat use among species was lower than expected by chance. Evidence that Herpsilochmus are spatially segregating reinforces the hypothesis of interspecific competition as the predominant force in the selection of microhabitat of the species. However, more data and experiments are necessary to state categorically that the observed pattern is a result of current or past competition / Como esp?cies similares ecologicamente s?o capazes de coexistir sempre gerou grande interesse na comunidade cient?fica. A teoria cl?ssica de nicho prev? que para que a coexist?ncia seja poss?vel as esp?cies devem segregar em alguma dimens?o do nicho ecol?gico, portanto levando a diferencia??o entre as esp?cies. No entanto, trabalhos recentes tem demonstrado que justamente esp?cies mais similares em algumas caracter?sticas ecol?gicas seriam mais capazes de coexistir (filtro ambiental). O conhecimento de como essas for?as atuam nas comunidades pode revelar estrat?gias de coexist?ncia, trazendo importantes informa??es para o manejo e conserva??o das esp?cies. Neste estudo testei essas hip?teses de coexist?ncia utilizando o par de esp?cies Herpsilochmus pectoralis e H. sellowi. Para isso utilizei modelos de nicho ecol?gico em alta resolu??o (50 x50 m).Identifiquei quais os fatores ambientais estudados melhor predizem a ocorr?ncia das esp?cies. Em seguida, calculei a sobreposi??o no uso de h?bitat pelas esp?cies e constru? modelos nulos para testar a hip?tese de segrega??o de nicho espacial. Ainda, calculei par?metros de seletividade do uso do h?bitat para testar se a esp?cie H. pectoralis (esp?cie de maior tamanho de corpo) ? menos seletiva que o H. sellowi (esp?cie de menor tamanho de corpo) como previsto na literatura para outras esp?cies.Os resultados rejeitam a equival?ncia ecol?gica entre as esp?cies, revelando que as esp?cies de Herpsilochmus exploram o habitat de forma diferenciada, possuindo nichos ambientais distintos. A hip?tese de filtro ambiental n?o foi evidenciada em nossas an?lises, sendo a sobreposi??o no uso do h?bitat observada entre as esp?cies menor do que o esperado ao acaso. Evid?ncias de que os Herpsilochmus est?o segregando espacialmente refor?a a hip?tese da competi??o interespec?fica como for?a predominante na sele??o de microh?bitat das esp?cies. No entanto, para afirmar categoricamente que o padr?o observado ? efeito de uma competi??o atual ou passada experimentos futuros s?o sugeridos

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2015-12-03T23:16:48Z No. of bitstreams: 1 AnaFlaviaLinsSouto_DISSERT.pdf: 1191835 bytes, checksum: f7fea5d276f29ff8f41cd847fd02f335 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2015-12-09T22:31:31Z (GMT) No. of bitstreams: 1 AnaFlaviaLinsSouto_DISSERT.pdf: 1191835 bytes, checksum: f7fea5d276f29ff8f41cd847fd02f335 (MD5) / Made available in DSpace on 2015-12-09T22:31:31Z (GMT). No. of bitstreams: 1 AnaFlaviaLinsSouto_DISSERT.pdf: 1191835 bytes, checksum: f7fea5d276f29ff8f41cd847fd02f335 (MD5) Previous issue date: 2014-11-10 / O presente trabalho tem como objetivo demonstrar a rela??o do princ?pio da efici?ncia -como expresso na Constitui??o Federal de 1988, atrav?s da Emenda Constitucional n? 19 - com as ag?ncias reguladoras, mais precisamente a ANATEL (Ag?ncia Nacional de Telecomunica??es). Abrange tamb?m a import?ncia que esse princ?pio possui sobre a regula??o - fiscalizar e gerenciar os servi?os p?blicos - e quando uma atividade ser? considerada eficiente, tendo em mente que as ag?ncias sujeitam-se aos demais princ?pios da Administra??o P?blica. O crescente uso da telefonia vem possibilitando um maior desenvolvimento de tecnologias que proporcionam melhorias na presta??o desse servi?o. O VoIP (Voice over IP), nada mais ? que um avan?o tecnol?gico que atinge diretamente as prestadoras do servi?o de telefonia convencional, tanto pela modifica??o dos neg?cios que trabalhavam por um longo per?odo com a mesma tecnologia, quanto pela quantidade de novos concorrentes que entram no mercado. Como ag?ncia reguladora do servi?o de telecomunica??es, a ANATEL, ainda n?o regulamentou o servi?o de telefonia de voz utilizando o protocolo IP. O que se aguarda com o passar dos anos ? que a ANATEL exer?a a sua fun??o regulat?ria para proporcionar melhores condi??es de competi??o entre as empresas prestadoras do VoIP e da telefonia convencional, obviamente que algumas dificuldades s?o esperadas, haja vista, que o VoIP ? uma tecnologia que abrange dois servi?os, tanto a telefonia convencional quanto a utiliza??o da internet / The present work aims to demonstrate the link of the principle of efficiency - as expressed in the Constitution of 1988, by Constitutional Amendment No. 19 - with regulatory agencies, more specifically the ANATEL (National Telecommunications Agency). It also includes this principle?s importance to regulation - to monitor and manage public services - as well as when an activity will be considered efficient, keeping in mind that agencies are subjected to other principles of public administration. The increasing use of telephony has enabled further development of technologies that provide improvements in the provision of this service. The VoIP (Voice over IP), is nothing more than a technological breakthrough that directly targets the providers of conventional telephone service, both by modifying the business working for a long time with the same technology as the amount of new competitors? dispute on market share. It also analyses the difficulty of understanding and definition of what is VoIP telephony, its growth and the threats that the traditional and mostly which is ANATEL?s role concerning this telephony technology. As regulator of the telecommunications service, ANATEL not yet regulated the voice telephony service using the IP protocol. What looks over the years is that ANATEL exercise its regulatory function to provide better conditions for competition among providers of VoIP and traditional telephone companies, obviously some difficulties are expected, given that VoIP is a technology that provides two services, through conventional telephony and using the internet.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-06-02T23:08:22Z No. of bitstreams: 1 JeanneRaquelDeAndradeFranco_DISSERT.pdf: 3675339 bytes, checksum: 97a2dabc11a0348c6acf6db2de294e5d (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-06-12T19:27:50Z (GMT) No. of bitstreams: 1 JeanneRaquelDeAndradeFranco_DISSERT.pdf: 3675339 bytes, checksum: 97a2dabc11a0348c6acf6db2de294e5d (MD5) / Made available in DSpace on 2017-06-12T19:27:50Z (GMT). No. of bitstreams: 1 JeanneRaquelDeAndradeFranco_DISSERT.pdf: 3675339 bytes, checksum: 97a2dabc11a0348c6acf6db2de294e5d (MD5) Previous issue date: 2017-02-14 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Manguezais s?o ecossistemas costeiros e estuarinos que pertencem a climas quentes e temperados ou tropicais ?midos, s?o dominados por esp?cies lenhosas, fornecem importantes bens e servi?os ecossist?micos e possuem valor socioecon?mico. Os manguezais s?o sens?veis a dist?rbios e est?o em constante processo de degrada??o devido ? carcinicultura e ao desenvolvimento urbano. Intera??es entre indiv?duos vegetais podem resultar em competi??o e facilita??o interferindo no crescimento, no padr?o de distribui??o e na sobreviv?ncia das plantas, al?m de modificar caracter?sticas f?sico-qu?micas do ambiente. Vari?veis abi?ticas e bi?ticas interagem permitindo an?lise da adapta??o das esp?cies em diferentes condi??es ambientais, podendo tamb?m inferir sobre a intensidade de degrada??o. O objetivo geral do estudo foi identificar os principais fatores limitantes no crescimento e na sobreviv?ncia de plantas de Rhizophora mangle L. (Rhizophoraceae) em dois ambientes dominados pela esp?cie e localizados em ?rea de carcinicultura, sendo um com presen?a de ?rvores e copa fechada, e outro aberto com plantas jovens e subarbustivas. Foram realizados dois monitoramentos com sele??o de parcelas e plantas em cada ambiente, totalizando 90 indiv?duos, para quantificar o crescimento ao longo do tempo atrav?s de medidas da altura, n?mero de ramos e di?metro a 30 cm do solo. Para as vari?veis abi?ticas foram feitas medidas da temperatura e pH do solo, luminosidade, salinidade, velocidade do vento, temperatura do ar e penetrabilidade do solo nas parcelas de cada ambiente aberto e fechado por 12 meses. Indiv?duos adultos de R. mangle foram competidores interferindo no crescimento de plantas jovens da mesma esp?cie atrav?s da limita??o de luz e do estresse advindo do ac?mulo de sedimentos. Em ambiente aberto, com plantas jovens apresentando mesma idade e distribu?das de forma agregada, ocorreu facilita??o com redu??o de condi??es estressantes devido ? maior incid?ncia de radia??o solar e temperatura desse ambiente, e tamb?m competi??o atrav?s de alta densidade de plantas. Devido a essas intera??es positivas e negativas agindo simultaneamente, o efeito final da densidade-depend?ncia no crescimento de plantas do ambiente aberto foi neutro. Al?m disso, temperaturas m?dias de 30?C, pH do solo com valores entre 5,5 e 6,5 e salinidade com cerca de 35 ppm foram fatores que beneficiaram o crescimento das plantas ao longo do tempo em ambiente aberto atrav?s da fotoss?ntese, de adapta??es fisiol?gicas e poss?vel melhor assimila??o de nutrientes do solo. Esses resultados ajudaram a entender as caracter?sticas ambientais que facilitam e interferem na recupera??o de ?reas degradadas pela carcinicultura. / Mangroves are ecosystems coastal and estuarine belonging to warm and temperate climates and wet tropics, mangroves are dominated by woody species, provide important ecosystem goods and services and have socioeconomic value. Mangroves are sensitive to disturbances and are constantly being degraded due to shrimp farming and to urban development. Interactions between plant individuals may result in competition and facilitation by interfering on the plant growth, pattern of distribution and plant survival, besides modifying physical-chemical characteristics of the environment. Abiotic and biotic variables interact allowing the analysis of the adaptation of the species in different environmental conditions and also about the intensity of degradation. The main objective of the study was to identify the main limiting factors on the growth and survival of Rhizophora mangle L. (Rhizophoraceae) plants in two environments dominated by this specie and located in the shrimp farming area, one with trees and closed canopy, and another open with young and sub-shrub plants. Two monitoring were carried out with selection of plots and plants in each environment, totaling 90 individuals, to quantify the growth over time by means of measures of height, number of branches and diameter at 30 cm. For the abiotic variables, measurements of soil temperature and pH, luminosity, salinity, wind velocity, air temperature and soil penetrability were taken in the plots of each open and closed environment for 12 months. Adult individuals of R. mangle were competitors interfering in the growth of young plants of the same species through the limitation of light and of the stress coming from the accumulation of sediments. In the open environment, with young plants presenting the same age and distributed in an aggregated way, facilitation occurred with reduction of stressful conditions due to the higher incidence of solar radiation and temperature of this environment, and also competition through high density of plants. Due to these positive and negative interactions acting simultaneously, the final effect of density dependence on plant growth of the open environment was neutral. However, mean temperatures of 30?C, soil pH values between 5.5 and 6.5 and salinity with about 35 ppm were factors that benefited the growth of the plants over time in open environment through photosynthesis, of physiological adaptations and possible better assimilation of soil nutrients. These results helped to understand the environmental characteristics that facilitate and interfere the recovery of areas degraded by shrimp farming.

Submitted by PPG Zoologia (zoologia-pg@pucrs.br) on 2018-07-26T17:32:12Z No. of bitstreams: 1 Dissertac?a?o de Mestrado_Thiago Cavalcante_2018.pdf: 1062183 bytes, checksum: df6896e683973408161b744df41a770f (MD5) / Approved for entry into archive by Sheila Dias (sheila.dias@pucrs.br) on 2018-08-01T12:02:05Z (GMT) No. of bitstreams: 1 Dissertac?a?o de Mestrado_Thiago Cavalcante_2018.pdf: 1062183 bytes, checksum: df6896e683973408161b744df41a770f (MD5) / Made available in DSpace on 2018-08-01T12:21:57Z (GMT). No. of bitstreams: 1 Dissertac?a?o de Mestrado_Thiago Cavalcante_2018.pdf: 1062183 bytes, checksum: df6896e683973408161b744df41a770f (MD5) Previous issue date: 2018-02-16 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Group living animals, like most primates, benefit from a reduction in predation risk and an improvement in their potential to compete for food with other groups. However, gregariousness also increases intragroup food competition that can modulate within-group agonism and interindividual spatial patterns. We evaluated the influence of fruit availability and consumption (degree of frugivory) on the agonistic behavior and interindividual distance in two populations of Gray woolly monkeys living in forest fragments in southwestern Brazilian Amazonia. We recorded 165 intragroup agonistic interactions in a feeding context via the ?all occurrences? method and 3,549 records of spacing via scan sampling. Fruit consumption presented a direct relationship with agonistic and spacing behavior, whereas our estimate of fruit availability was a good predictor only for spacing. Woolly monkey selection of food patches composed of trees with diameter at breast height almost fourfold than that of the trees found in the phenology plots might explain the lack of relationship between fruit availability and agonism. The proportion of time (50%) that woolly monkeys had no nearby (<5 m) neighbors is compatible with a strategy of reducing intragroup fruit competition by managing interindividual distances. In sum, we presented the first evidence of aggressive intragroup feeding competition in Lagothrix cana and demonstrate the influence of fruit availability and consumption on some aspects of the social system of woolly monkeys. / Animais que vivem em grupo, como a maioria dos primatas, s?o beneficiados por uma redu??o no risco de preda??o e um aumento na possibilidade de defesa cooperativa dos recursos. Por?m, a vida em sociedade aumenta a competi??o intragrupo por alimento, a qual pode modular as intera??es agon?sticas e o espa?amento interindividual. Avaliamos a influ?ncia da disponibilidade de frutos e seu consumo (grau de frugivoria) no comportamento agon?stico e espa?amento interindividual de duas popula??es de macacos-barrigudos em fragmentos florestais na Amaz?nia brasileira. Registramos 165 intera??es agon?sticas intragrupo no contexto de alimenta??o via m?todo de ?todas as ocorr?ncias? e 3549 registros de espa?amento via m?todo de ?varredura instant?nea?. O consumo de frutos apresentou uma rela??o direta com o comportamento agon?stico e o espa?amento interindividual, enquanto a disponibilidade de frutos foi um bom preditor apenas do espa?amento. A explora??o pelos barrigudos de locais de alimenta??o com ?rvores com di?metro ? altura do peito quase quatro vezes maior do que as ?rvores monitoradas para a an?lise da disponibilidade de frutos pode explicar a aus?ncia de rela??o com o agonismo. A propor??o do tempo (50%) na qual os barrigudos estiveram sem vizinhos pr?ximos (<5 m) ? compat?vel com uma estrat?gia de redu??o da competi??o intragrupo por frutos via manuten??o do distanciamento interindividual. Em suma, apresentamos as primeiras evid?ncias de competi??o agressiva intragrupo para Lagothrix cana e demonstramos a import?ncia da disponibilidade e consumo de frutos em moldar alguns aspectos do sistema social dos barrigudos.

Submitted by PPG Ci?ncia da Computa??o (ppgcc@pucrs.br) on 2018-08-22T17:04:33Z No. of bitstreams: 1 LETICIA_SANTOS_MACHADO_TES.pdf: 7715415 bytes, checksum: 7658ad49d27e7fdfea1a76aeee1ca834 (MD5) / Approved for entry into archive by Sheila Dias (sheila.dias@pucrs.br) on 2018-08-24T18:53:57Z (GMT) No. of bitstreams: 1 LETICIA_SANTOS_MACHADO_TES.pdf: 7715415 bytes, checksum: 7658ad49d27e7fdfea1a76aeee1ca834 (MD5) / Made available in DSpace on 2018-08-24T19:23:50Z (GMT). No. of bitstreams: 1 LETICIA_SANTOS_MACHADO_TES.pdf: 7715415 bytes, checksum: 7658ad49d27e7fdfea1a76aeee1ca834 (MD5) Previous issue date: 2018-03-28 / Software Crowdsourcing (SW CS) ? uma estrat?gia emergente de desenvolvimento de software onde um grande n?mero de pessoas tem se engajado para contribuir em v?rias atividades de software. Tal estrat?gia (baseada na multid?o), tem sido utilizada pelas empresas que est?o buscando aumentar a velocidade de seus esfor?os em desenvolvimento de software. SW CS est? geralmente estruturado em torno de plataformas que permitem que um solicitante submeta uma tarefa e conecte-a com uma multid?o de pessoas que ir? pr?ver solu??es para a tarefa. Essas plataformas geralmente exploram uma abordagem competitiva para realiza??o da tarefa: membros da multid?o, independentemente, criam uma solu??o para a tarefa enquanto competem uns contra os outros em busca de uma premia??o financeira ao final da tarefa entregue. Uma vez que a competi??o pode reduzir a colabora??o, recentes estudos, surpreendentemente, indicam que a colabora??o existe em plataformas de SW CS. Estes estudos t?m focado em dois aspectos. O primeiro, em problemas de colabora??o entre plataforma e solicitante com rela??o a atribui??o da multid?o e as tarefas a serem desenvolvidas nos desafios de competi??o (aloca??o e submiss?o de tarefas) e, o segundo aspecto, relacionado ao impacto da colabora??o entre membros da multid?o e a qualidade das solu??es submetidas. Outros aspectos referentes a colabora??o entre os membros da multid?o ainda s?o amplamente inexplorados. Nessa tese, nosso objetivo ? identificar barreiras e caracter?sticas de colabora??o enfrentadas pelos membros da multid?o em SW CS competitivo. Para alcan?ar este objetivo, n?s conduzimos m?ltiplos estudos utilizando diferentes m?todos de pesquisa divididos em duas fases: explorat?ria e avaliatoria. Para a fase explorat?ria, os dados coletados foram obtidos a partir de: (i) partes envolvidas em projetos de SW CS (solicitante, multid?o e plataforma) atrav?s de entrevistas semi-estruturadas com profissionais e empresas, (ii) estudos selecionados atrav?s da revis?o da literatura e; (iii) estudo emp?rico sobre como desenvolvedores colaboram entre si em uma plataforma de SW CS competitivo ? TopCoder. A barreira de colabora??o mais frequente encontrada est? associada a falta de comunica??o apropriada entre as partes. Baseado nessa barreira decidimos na fase avaliat?ria conduzir uma (iv) an?lise qualitativa do principal canal de comunica??o utilizado pela multid?o: f?rums hospedados na plataforma TopCoder e, finalmente, (v) realizamos um survey destinado aos desenvolvedores que competiram na TopCoder para avaliar a influ?ncia da colabora??o no desempenho da tarefa. Os resultados obtidos nos estudos avaliat?rios sugerem que a colabora??o entre os membros da multid?o est? correlacionada com a entrega de solu??es de software vencedoras nos desafios de SW CS. / Software Crowdsourcing (SW CS) is an emergent software development strategy where a large number of people have been engaged to contribute in several software activities. Such strategy (based on the crowd), has been used for companies who are seeking to increase the speed of their software development efforts. This strategy is usually structured around platforms that allow a requester submit a task to be performed and connect with the crowd that assigned and provide a solution for the task. These platforms usually explore a competitive approach: members of the crowd independently create a solution while compete against each other by monetary rewards for task completion. While competition usually reduces collaboration, some recent studies surprisingly indicate that there is collaboration in SW CS platforms. These studies have focused on two aspects. First, collaboration concerns between platform and requester in terms of crowd?s assignment to the challenges (task allocation and submission) and second, the impact of the collaboration among crowd members in the quality of the submitted solutions. Other aspects of the collaboration among crowd members have been largely unexplored. In this thesis, our goal is to identify collaboration?s characteristics and barriers faced by crowd members in competitive software crowdsourcing. To achieve this goal, we have conducted multiple studies, using mixed research methods divided in two phases: one exploratory and one evaluatory. For the exploratory phase, we used data collected from: (i) the three involved parties in SW CS projects (requester, crowd and platform) through semi structured interviews with practitioners and companies, (ii) studies selected via literature review; and (iii) an empirical study about how developer collaborated with each other in a SW CS competitive platform ? TopCoder. The most frequent collaboration barrier was associated to lack of proper communication among the parties. Based on this barrier we decided, in the evaluatory phase, to conduct a (iv) qualitative analysis of the main communication channel used by the crowd: forums hosted on TopCoder platform and (v) a survey aimed at developers who had competed on TopCoder to assess the influence of collaboration in task performance. Our results from these evaluatory studies suggest that collaboration among crowd members is correlated with delivering winning solutions in SW CS challenges.