Construção de tabelas verdade - Parte 3

O vídeo explica a construção de uma tabela verdade através de uma proposição composta. O primeiro passo é definir os valores de cada variável de forma direta. Depois, definir as colunas de cada sub-fórmula e preencher as colunas aplicando operadores, e com isso, definir os valores lógicos da proposição final.

Associação do envolvimento físico com níveis de obesidade, aptidão física, actividades sedentárias e participação desportiva: um estudo em alunos dos 2º e 3º Ciclos, e Ensino Secundário de um concelho rural da RAM

O presente trabalho é constituído por dois estudos, sendo que o primeiro prende-se com a adaptação e quantificação da fiabilidade de um instrumento que visa caracterizar o envolvimento físico. O segundo estudo é constituído pela caracterização de uma amostra de jovens, no que se refere a essas variáveis do envolvimento, níveis de aptidão física, participação em actividades sedentárias e actividades desportivas, bem como da relação entre estes parâmetros. Metodologia do primeiro estudo: A amostra do primeiro estudo é constituída por 106 indivíduos de ambos os sexos (50 rapazes e 56 raparigas) do 7º ano de escolaridade. O instrumento validado por Evenson et al. (2006), foi traduzido para a língua Portuguesa, e testado para a fiabilidade através da sua aplicação em dois momentos, com uma semana de intervalo. Foi verificada a consistência interna, níveis de concordância e percentagens de acordos entre os dois momentos de avaliação. Metodologia do segundo estudo: A amostra do segundo estudo é composta por 296 indivíduos (150 do sexo masculino e 146 do sexo feminino) com idades compreendidas entre os 10 e os 18 anos (com uma média de idades de 13,6 + 1,9 anos). A classificação do IMC foi determinada pelos valores referenciados por Cole et al. (2000 e 2007). As avaliações normativas e criteriais da %MG foram obtidas pelas equações de Slaughter et al. (1988) e níveis de classificação de Lohman (1987), respectivamente. A aptidão física foi avaliada pela bateria de testes Fitnessgram (The Cooper Institute for Aerobics Research, 1999) e pela bateria de testes Eurofit (Adam et al., 1988). A variável grupo de prática desportiva foi determinada com base num questionário individual. A participação em actividades sedentárias foi determinada pela aplicação do questionário auto reportado. O envolvimento foi caracterizado com base no questionário de Evenson et al. (2006) traduzido para português. Resultados: Entre os dois momentos de avaliação, foram verificados bons níveis de concordância e uma boa consistência interna. As percentagens de acordos registadas estavam entre o razoável e o significativo, sendo estes valores similares aos apresentados por Evenson et al. (2006). A taxa de prevalência para o excesso de peso e obesidade foi de 26%, e para a %MG moderadamente alta, alta ou muito alta, foi de 53%. Ao nível dos testes motores, mais de metade da amostra classificou-se abaixo da ZAFS nos testes do vaivém, dos abdominais e da suspensão na barra. Em relação à participação desportiva, 54,4% da amostra tem como única actividade física organizada, as aulas de educação física e os restantes praticam algum tipo de actividade desportiva fora ou dentro da escola. Em relação às actividades sedentárias, 23,4% dos inquiridos afirmaram passar mais de 4 horas diárias neste tipo de actividades. Ao nível do envolvimento detectamos diferenças para o sexo e EE para apenas em alguns itens do questionário. Verificaram-se correlações significativas entre as variáveis estudadas, em nomeadamente entre os %MG e os testes motores, bem como entre os %MG e o envolvimento natural e o transporte activo.

A confiança interorganizacional nas compras

This research is part of the field of organizational studies, focusing on organizational purchase behavior and, specifically, trust interorganizational at the purchases. This topic is current and relevant by addressing the development of good relations between buyer-supplier that increases the exchange of information, increases the length of relationship, reduces the hierarchical controls and improves performance. Furthermore, although there is a vast literature on trust, the scientific work that deal specifically at the trust interorganizational still need further research to synthesize and validate the variables that generate this phenomenon. In this sense, this investigation is to explain the antecedents of trust interorganizational by the relationship between the variable operational performance, organizational characteristics, shared values and interpersonal relationships on purchases by manufacturing industries, in order to develop a robust literature, most consensual, that includes the current sociological and economic, considering the effect of interpersonal relationships in this phenomenon. This proposal is configured in a new vision of the antecedents of interorganizational trust, described as significant quantitative from models Morgan and Hunt (1994), Doney and Cannon (1997), Zhao and Cavusgil (2006) and Nyaga, Whipple, Lynch (2011), as well as qualitative analysis of Tacconi et al. (2011). With regard to methodological aspects, the study assumes the form of a descriptive, survey type, and causal trace theoretical and empirical. As for his nature, the investigation, explicative character, has developed a quantitative approach with the use of exploratory factor analysis and structural equation modeling SEM, with the use of IBM software SPSS Amos 18.0, using the method of maximum verisimilitude, and supported by technical bootstraping. The unit of analysis was the buyer-supplier relationship, in which the object under investigation was the supplier organization in view of the purchasing company. 237 valid questionnaires were collected among key informants, using a simple random sampling developed in manufacturing industries (SIC 10-33), located in the city of Natal and in the region of Natal. The first results of descriptive analysis demonstrate the phenomenon of interorganizational trust, in which purchasing firms believe, feel secure about the supplier. This demonstration showed high levels of intensity, predominantly among the vendors that supply the company with materials that are used directly in the production process. The exploratory and confirmatory factor analysis, performed on each variable alone, generated a set of observable and unobservable variables more consistent, giving rise to a model, that needed to be further specified. This again specify model consists of trajectories was positive, with a good fit, with a composite reliability and variance extracted satisfactory, and demonstrates convergent and discriminant validity, in which the factor loadings are significant and strong explanatory power. Given the findings that reinforce the model again specify data, suggesting a high probability that this model may be more suited for the study population, the results support the explanation that interorganizational trust depends on purchases directly from interpersonal relationships, sharing value and operating performance and indirectly of personal relationships, social networks, organizational characteristics, physical and relational aspect of performance. It is concluded that this trust can be explained by a set of interactions between these three determinants, where the focus is on interpersonal relationships, with the largest path coefficient for the factor under study

Fatores críticos de sucesso como antecedentes da aceitação de um sistema de informação em uma universidade federal

In recent decades the public sector comes under pressure in order to improve its performance. The use of Information Technology (IT) has been a tool increasingly used in reaching that goal. Thus, it has become an important issue in public organizations, particularly in institutions of higher education, determine which factors influence the acceptance and use of technology, impacting on the success of its implementation and the desired organizational results. The Technology Acceptance Model - TAM was used as the basis for this study and is based on the constructs perceived usefulness and perceived ease of use. However, when it comes to integrated management systems due to the complexity of its implementation,organizational factors were added to thus seek further explanation of the acceptance of such systems. Thus, added to the model five TAM constructs related to critical success factors in implementing ERP systems, they are: support of top management, communication, training, cooperation, and technological complexity (BUENO and SALMERON, 2008). Based on the foregoing, launches the following research problem: What factors influence the acceptance and use of SIE / module academic at the Federal University of Para, from the users' perception of teachers and technicians? The purpose of this study was to identify the influence of organizational factors, and behavioral antecedents of behavioral intention to use the SIE / module academic UFPA in the perspective of teachers and technical users. This is applied research, exploratory and descriptive, quantitative with the implementation of a survey, and data collection occurred through a structured questionnaire applied to a sample of 229 teachers and 30 technical and administrative staff. Data analysis was carried out through descriptive statistics and structural equation modeling with the technique of partial least squares (PLS). Effected primarily to assess the measurement model, which were verified reliability, convergent and discriminant validity for all indicators and constructs. Then the structural model was analyzed using the bootstrap resampling technique like. In assessing statistical significance, all hypotheses were supported. The coefficient of determination (R ²) was high or average in five of the six endogenous variables, so the model explains 47.3% of the variation in behavioral intention. It is noteworthy that among the antecedents of behavioral intention (BI) analyzed in this study, perceived usefulness is the variable that has a greater effect on behavioral intention, followed by ease of use (PEU) and attitude (AT). Among the organizational aspects (critical success factors) studied technological complexity (TC) and training (ERT) were those with greatest effect on behavioral intention to use, although these effects were lower than those produced by behavioral factors (originating from TAM). It is pointed out further that the support of senior management (TMS) showed, among all variables, the least effect on the intention to use (BI) and was followed by communications (COM) and cooperation (CO), which exert a low effect on behavioral intention (BI). Therefore, as other studies on the TAM constructs were adequate for the present research. Thus, the study contributed towards proving evidence that the Technology Acceptance Model can be applied to predict the acceptance of integrated management systems, even in public. Keywords: Technology

Cinemática de partículas em fluidos de viscosidade variável com o tempo e sua aplicação na construção de poços de petróleo: avaliação durante paradas operacionais

The new oil reservoirs discoveries in onshore and ultra deep water offshore fields and complex trajectories require the optimization of procedures to reduce the stops operation during the well drilling, especially because the platforms and equipment high cost, and risks which are inherent to the operation. Among the most important aspects stands out the drilling fluids project and their behavior against different situations that may occur during the process. By means of sedimentation experiments, a correlation has been validated to determe the sedimentation particles velocity in variable viscosity fluids over time, applying the correction due to effective viscosity that is a shear rate and time function. The viscosity evolution over time was obtained by carrying out rheologic tests using a fixed shear rate, small enough to not interfere in the fluid gelling process. With the sedimentation particles velocity and the fluid viscosity over time equations an iterative procedure was proposed to determine the particles displacement over time. These equations were implemented in a case study to simulate the cuttings sedimentation generated in the oil well drilling during stops operation, especially in the connections and tripping, allowing the drilling fluid project in order to maintain the cuttings in suspension, avoiding risks, such as stuck pipe and in more drastic conditions, the loss of the well

Metodologia para avaliação de cinemática de partículas gasosas em fluidos de viscosidade variável com o tempo e sua aplicação na construção de poços de petróleo

Many challenges have been presented in petroleum industry. One of them is the preventing of fluids influx during drilling and cementing. Gas migration can occur as result of pressure imbalance inside the well when well pressure becomes lower than gas zone pressure and in cementing operation this occurs during cement slurry transition period (solid to fluid). In this work it was developed a methodology to evaluate gas migration during drilling and cementing operations. It was considered gel strength concept and through experimental tests determined gas migration initial time. A mechanistic model was developed to obtain equation that evaluates bubble displacement through the fluid while it gels. Being a time-dependant behavior, dynamic rheological measurements were made to evaluate viscosity along the time. For drilling fluids analyzed it was verified that it is desirable fast and non-progressive gelation in order to reduce gas migration without affect operational window (difference between pore and fracture pressure). For cement slurries analyzed, the most appropriate is that remains fluid for more time below critical gel strength, maintaining hydrostatic pressure above gas zone pressure, and after that gels quickly, reducing gas migration. The model developed simulates previously operational conditions and allow changes in operational and fluids design to obtain a safer condition for well construction

Voleibol brasileiro : parâmetros fenotípicos e genotípicos na seleção de atletas

Objective: Identify phenotype and genotype parameters of female volleyball players at different performance levels to help in player selection. Methods: We identified characteristics of phenotype and genotype using the somatotype method (Heath Carter); anthropometry (weight, height and fat percentage); dermatoglyphics (Cummins and Midlo s method) as well as applying physical quality tests (Shuttle Run to assess agility and the Sargent Jump Test adapted for spike and block reach). The sample was composed of 179 players (54 from national teams and 125 from state teams). Results: Somatotype was similar among the performance levels in the mesomorphic component. The Height and ectomorphic component were greater in national team players as was spike and block reach. The vertical jump height for the spike was similar between the national under-17 team and the state teams observed, but in the block jump the lower level players were better. The dermatoglyphics characteristics identified were similar among the groups studied. Conclusions: The results of the variables studied show that somatotype, height, spike reach and block reach are fundamental parameters in player selection and in the specific characteristics of each game position of this sport. This paper proposes a multidisciplinary approach applicable in the fields of physical education, medicine and nutrition

Efetividade do flúor e da escovação e eficácia dos materiais de colagem ionômero de vidro e resina composta na reversão das microporosidades criadas pelo condicionamento ácido no esmalte dentário

The objectives of this clinical study was to evaluate the use of the toothpaste with fluoride and without fluoride and the daily tooth brushing are effective in the reversion of the dental enamel conditioned by acid. Another objective of this clinical study was to evaluate if the positioning of orthodontic accessories with glass ionomer cement helps in the reversion of the dental enamel conditioned by acid, when compared to composed resin. One hundred and twenty teeth were selected with indication of extraction by orthodontic reasons. The 30 volunteers were divided, randomly, in two groups. A group used toothpaste without fluoride and the other with it. The teeth of the sample were shuffled, in each volunteer. The teeth were conditioned by the 37% orthophosphoric acid. One of the conditioned teeth stayed in the mouth and suffered action of the abrasion for the tooth brushing, in another teeth a stainless steel mesh protection was positioned with glass ionomer cement, in another tooth the screen was glued with composed resin, in a fourth tooth (the control) was only conditioned after the extractions, 60 days later. All the teeth were appraised through DIAGNOdent, MEVA and EDS. In the obtained data it was possible to observe that there were not statistic significant differences in any comparison, even in the group that did not have access to the fluoride in the toothpaste as in the other that had. According with the used methodology, it was possible to observe too that there was not statistic significant differences in any comparison, even in the group that had the stainless steel mesh positioned with glass ionomer cement as in the group that the stainless steel mesh was positioned with composed resin. However, it was observed that there was an improvement in the topography of the enamel in all the teeth. The accomplishment of this study was facilitated due to the participation of the researchers' of the health area (dentistry), materials engineer, physics and chemistry. The researchers were originating from the Federal University of Rio Grande do Norte and of the University of Queensland, in Australia. This interdisciplinary group was decisive in the accomplishment of the study. It can be concluded that the enamel tends to return to its initial aspect, even if the patient does not have access to fluoride. That is probably due the action of the abrasion for the tooth brushing and mastication. In spite of it not being significant, it is suggested that the conditioned enamel was more resistant to the abrasion in the group that had access to fluoride. It was also possible to conclude that the fluoride liberated by the glass ionomer was not enough to provide a significant difference in the enamel conditioned by the acid, when compared with the composed resin, even in the group that did not use fluoride in the toothpaste as in the group that used

Fatores determinantes da decisão sobre a prática da cesariana em Natal-RN

O objetivo deste estudo é analisar os fatores que contribuíram para as diferentes decisões para o parto cesáreo e a ligadura de trompas entre as mulheres de 18 a 45 anos de idade no Município de Natal, no Nordeste do Brasil, no ano de 2000. Tratou-se de um estudo longitudinal, originado da base de dados de um Estudo Multicêntrico, envolvendo outras localidades do Brasil, composta de mulheres em idade fértil que procuraram o serviço público ou privado. Foram realizadas três entrevistas: no início da gestação, no mês anterior à data provável do parto e até um mês após o parto, perfazendo um total de 433 entrevistas, sendo finalizada com uma amostra de 269 mulheres. O estudo satisfez a um critério de elegibilidade, abrangendo uma amostra das mulheres de 18 a 40 anos de idade, que residiam em Natal e que estavam grávidas no máximo, na 22a semana de gestação, e procuraram o serviço público ou privado para a realização do pré-natal. Não entraram no estudo, aquelas mulheres que faziam um acompanhamento em ambulatórios especiais (hipertensão ou diabetes gestacional, HIV/AIDS). A análise consistiu, primeiramente, num estudo descritivo, seguido de uma discussão sobre a trajetória do desejo à realização do parto e testou-se a significância estatística dos partos com variáveis socioeconômicas. Sequencialmente adotou-se uma análise bivariada centrada nos testes de associação, onde foi considerada a variável tipo de parto como sendo a variável resposta e as demais variáveis, relacionadas à condição sóciodemográfica e a saúde reprodutiva da mulher, como sendo as variáveis de risco ou independentes. Para o cálculo da razão de chance (OR), foi utilizado o modelo de regressão logística múltipla. Das 269 mulheres entrevistadas, 56,0% foram submetidas ao parto normal. Este tipo de parto foi desejado independente da categoria, por 71% das entrevistadas. Os resultados mostraram como fatores determinantes para cesárea, o serviço ser privado (OR = 5,6), a mulher ter idade acima de 20 anos (OR=2,87), ser primípara (OR=4,56) e a realização de ligadura de trompas (OR=12,94). Independente da parturição, 84% das mulheres do serviço público foram submetidas a um parto normal, enquanto que, 74% das primíparas do serviço privado, fizeram uma cesárea. Os resultados sinalizam um distanciamento efetivo entre o desejo por um tipo de parto e a sua realização, quando os fatores considerados, não foram somente técnicos, podendo, também, refletir a falta de prática do parto normal, pelo obstetra e a necessidade de uma maior consciência ética nos procedimentos obstétricos, de modo a favorecer uma maior abertura na participação da gestante na escolha pelo tipo de parto

Variabilidade espacial de atributos químicos de um argissolo para aplicação de insumos à taxa variável em diferentes formas de relevo

A agricultura de precisão implica análise da variabilidade espacial de fatores de produção e a aplicação de insumos de forma localizada. Várias são as causas que condicionam a variabilidade espacial dos solos, sendo o relevo um dos fatores mais importantes. O presente estudo teve por objetivo analisar a variabilidade espacial dos atributos químicos do solo e a elaboração de mapas de necessidade de aplicação de insumos de forma localizada, em áreas com diferentes formas de relevo. Duas parcelas de 1 ha cada foram delimitadas em áreas com topografia côncava e convexa. Foram retiradas, em cada área, 242 amostras de solos em 121 pontos, nas profundidades de solo de 0,00-0,20 m e 0,20-0,40 m. Os resultados de análise química foram submetidos às análises da estatística descritiva, geoestatística e interpolação por krigagem. A área convexa apresentou maior variabilidade espacial do solo em relação a área côncava. A adoção da agricultura de precisão possibilitou economia de aproximadamente 25 kg ha-1 de P2O5 na área côncava.

Avaliação da Usabilidade de Interfaces Web segundo Critérios Ergonômicos de Bastien e Scapin: Pesquisa com os Ambientes Virtuais de Educação à Distância Aulanet, E-Proinfo e Teleduc

Este trabalho tem dois objetivos: avaliar a usabilidade de três interfaces de ambientes virtuais de educação à distância através de duas técnicas avaliativas e identificar os fatores influenciadores da percepção de usabilidade dos ambientes avaliados. Os sistemas de educação à distância escolhidos foram o AulaNet, o E-Proinfo e o Teleduc, por serem desenvolvidos no Brasil e terem distribuição gratuita. A avaliação da usabilidade foi realizada através de duas técnicas documentadas na literatura. A primeira técnica de avaliação, do tipo preditiva ou diagnóstica, foi realizada pelo autor e um concluinte do curso de Sistemas de Informação do Centro Federal de Educação Tecnológica do estado do Piauí (CEFET-PI), mediante a observação de um checklist denominado Ergolist. A segunda avaliação, do tipo prospectivo, foi efetivada com o usuário sendo o próprio avaliador das interfaces, através de um questionário. A amostra foi composta de 15 professores e 15 alunos do CEFET-PI. Os resultados colhidos foram analisados a partir da estatística descritiva e testes de chi-quadrado. Os resultados mostraram que os ambientes apresentarem problemas de adaptabilidade, pois não possuem flexibilidade e nem levam em consideração a experiência do usuário. Na análise inferencial, foi constatado que o tempo de uso da Internet não afetou significativamente sua avaliação da usabilidade dos três ambientes, assim como na maior parte das variáveis de usabilidade não foram influenciadas pelo tipo de usuário , sexo e escolaridade . Por outro lado, em vários dos critérios ergonômicos avaliados, as variáveis de sistema tipo de ambiente e experiência com computador e a variável demográfica faixa etária afetaram a percepção de usabilidade dos ambientes virtuais de educação à distância

Modelagem de dados de falhas de equipamentos de sub-superfície em poços de petróleo da Bacia Potiguar

This master´s thesis presents a reliability study conducted among onshore oil fields in the Potiguar Basin (RN/CE) of Petrobras company, Brazil. The main study objective was to build a regression model to predict the risk of failures that impede production wells to function properly using the information of explanatory variables related to wells such as the elevation method, the amount of water produced in the well (BSW), the ratio gas-oil (RGO), the depth of the production bomb, the operational unit of the oil field, among others. The study was based on a retrospective sample of 603 oil columns from all that were functioning between 2000 and 2006. Statistical hypothesis tests under a Weibull regression model fitted to the failure data allowed the selection of some significant predictors in the set considered to explain the first failure time in the wells

Estabilidade e robustez de um controlador adaptativo indireto por um modelo de referência e estrutura variável

In this thesis, it is developed the robustness and stability analysis of a variable structure model reference adaptive controller considering the presence of disturbances and unmodeled dynamics. The controller is applied to uncertain, monovariable, linear time-invariant plants with relative degree one, and its development is based on the indirect adaptive control. In the direct approach, well known in the literature, the switching laws are designed for the controller parameters. In the indirect one, they are designed for the plant parameters and, thus, the selection of the relays upper bounds becomes more intuitive, whereas they are related to physical parameters, which present uncertainties that can be known easier, such as resistances, capacitances, inertia moments and friction coefficients. Two versions for the controller algorithm with the stability analysis are presented. The global asymptotic stability with respect to a compact set is guaranteed for both cases. Simulation results under adverse operation conditions in order to verify the theoretical results and to show the performance and robustness of the proposed controller are showed. Moreover, for practical purposes, some simplifications on the original algorithm are developed

Avaliação de robustez, desempenho e aplicação do controlador adaptativo por posicionamento de pólos e estrutura variável

In this work, the variable structure adaptive pole placement controller (VS-APPC) robustness and performance are evaluated and this algorithm is applied in a motor control system. The controller robustness evaluation will be done through simulations, where will be introduced in the system the following adversities: time delay, actuator response boundeds, disturbances, parametric variation and unmodeled dynamics. The VS-APPC will be compared with PI control, pole placement control (PPC) and adaptive pole placement controller (APPC). The VS-APPC will be simulated to track a step and a sine reference. It will be applied in a three-phase induction motor control system to track a sine signal in the stator reference frame. Simulation and experimental results will prove the efficiency and robustness of this control strategy

Uma proposta de regulador nebuloso para geradores eólicos de indução

This work presents a proposal for a voltage and frequency control system for a wind power induction generator. It has been developed na experimental structure composes basically by a three phase induction machine, a three phase capacitor and a reactive static Power compensator controlled by histeresys. lt has been developed control algorithms using conventional methods (Pl control) and linguistic methods (using concepts of logic and fuzzy control), to compare their performances in the variable speed generator system. The control loop was projected using the ADJDA PCL 818 model board into a Pentium 200 MHz compu ter. The induction generator mathematical model was studied throught Park transformation. It has been realized simulations in the Pspice@ software, to verify the system characteristics in transient and steady-state situations. The real time control program was developed in C language, possibilish verify the algorithm performance in the 2,2kW didatic experimental system