Estimação e compensação de não linearidades inerentes aos atuadores dos processos industriais

The oscillations presents in control loops can cause damages in petrochemical industry. Canceling, or even preventing such oscillations, would save up to large amount of dollars. Studies have identified that one of the causes of these oscillations are the nonlinearities present on industrial process actuators. This study has the objective to develop a methodology for removal of the harmful effects of nonlinearities. Will be proposed an parameter estimation method to Hammerstein model, whose nonlinearity is represented by dead-zone or backlash. The estimated parameters will be used to construct inverse models of compensation. A simulated level system was used as a test platform. The valve that controls inflow has a nonlinearity. Results and describing function analysis show an improvement on system response

Economia do petróleo e desenvolvimento: estudo exploratório sobre as perspectivas do pré-sal brasileiro

A pesquisa analisa as possibilidades abertas pela exploração de petróleo na camada pré-sal, avaliando de que maneira a expansão do setor petrolífero poderá acelerar o crescimento econômico brasileiro e contribuir para novas estratégias de desenvolvimento. A hipótese inicial é que o Brasil enfrenta uma restrição estrutural de balanço de pagamentos, que poderá ser amenizada pela diminuição das importações de petróleo e derivados e pelo aumento do valor exportado no setor. Para avaliá-la são resgatados aspectos históricos e geopolíticos relacionados ao petróleo, assim como são tratadas as características microeconômicas dos recursos naturais não renováveis. Também se consideram questões de ordem macroeconômica, como a especialização produtiva da economia brasileira e sua inserção no comércio internacional, discutindo como o desenvolvimento da indústria petrolífera poderá afetá-las. Para tanto, a investigação fundamenta-se na teoria estruturalista e nos modelos de crescimento com ênfase na restrição externa. O trabalho examina ainda os casos da Rússia, Venezuela e México para avaliar a experiência de países exportadores de petróleo. Como contribuição, um modelo de crescimento é utilizado para realizar simulações acerca do Brasil, cobrindo o período 2013-2020 com a formulação de três cenários. A partir dos resultados discute-se que a necessidade de consecução das metas fiscal e de inflação pode desencadear políticas restritivas que limitam a utilização da folga fiscal e externa, oriundas do pré-sal, para induzir o crescimento. Conclui-se que um círculo virtuoso de desenvolvimento com mudança estrutural depende não apenas da modernização produtiva, mas também, e principalmente, da evolução político-institucional do país

Análise da atividade de trabalho profissional de gerentes de hotel à luz da abordagem da ergonomia

This Masters degree dissertation presents a research that aims at analyzing the activities regarding within a hotel managers work in Natal/RN - Brazil, This Masters degree dissertation presents the research that aims at analyzing the activities regarding the hotel managers work in Natal / RN - Brazil, performing diagnosis of their activities and relating the aspects that impact the quality and productivity of hotel services and managers occupational health. This research is characterized as a case study with a qualitative approach, taking the method of Ergonomic Work Analysis which is the analysis of the managers work activity as a reference to the focus; and combining the use of observational and interactional methods. Ergonomics and macroergonomics are used in this study not only to understand the physical, cognitive and organizational constraints of the manager s duties, but also to characterize the work organizational architecture and design of that hotel. High workload, accumulation of tasks and diversion of functions performed by managers were noticed, increasing thereby the physical and psychological suffering for them. It was found that the activity of managers is characterized by the ambivalence of power, limited autonomy, cooperation, interdependence between managers and the fear of incompetence. It was also noticed that managers devote more time to the day job (37%), another time to sleep (30%), while only 33% of the rest of the day are meant for activities like taking care of health, family, social life and study. Although there are few studies addressing the health and safety of hotel managers, this research revealed that 84% of the surveyed hotel managers complain of musculoskeletal pain which 50% are obese and are 100% sedentary. It was also observed that managers adopt unsuitable postures for carrying out the work activities that contribute to becoming injured or work-related musculoskeletal disorders in the near future. Ergonomic measures were recommended as an investment in the skills and the training of managers, encouraging cooperative work, appropriateness of workload, limiting overtime, preserving the enjoyment of breaks during work and weekly holidays, changing the layout of the work sector , usage of communication technology to prevent displacement, compensatory physical activities, furniture adaptation, among others

Simulação computacional da interação fluido-estrutura em bombas de cavidades progressivas

The pumping through progressing cavities system has been more and more employed in the petroleum industry. This occurs because of its capacity of elevation of highly viscous oils or fluids with great concentration of sand or other solid particles. A Progressing Cavity Pump (PCP) consists, basically, of a rotor - a metallic device similar to an eccentric screw, and a stator - a steel tube internally covered by a double helix, which may be rigid or deformable/elastomeric. In general, it is submitted to a combination of well pressure with the pressure generated by the pumping process itself. In elastomeric PCPs, this combined effort compresses the stator and generates, or enlarges, the clearance existing between the rotor and the stator, thus reducing the closing effect between their cavities. Such opening of the sealing region produces what is known as fluid slip or slippage, reducing the efficiency of the PCP pumping system. Therefore, this research aims to develop a transient three-dimensional computational model that, based on single-lobe PCP kinematics, is able to simulate the fluid-structure interaction that occurs in the interior of metallic and elastomeric PCPs. The main goal is to evaluate the dynamic characteristics of PCP s efficiency based on detailed and instantaneous information of velocity, pressure and deformation fields in their interior. To reach these goals (development and use of the model), it was also necessary the development of a methodology for generation of dynamic, mobile and deformable, computational meshes representing fluid and structural regions of a PCP. This additional intermediary step has been characterized as the biggest challenge for the elaboration and running of the computational model due to the complex kinematic and critical geometry of this type of pump (different helix angles between rotor and stator as well as large length scale aspect ratios). The processes of dynamic generation of meshes and of simultaneous evaluation of the deformations suffered by the elastomer are fulfilled through subroutines written in Fortan 90 language that dynamically interact with the CFX/ANSYS fluid dynamic software. Since a structural elastic linear model is employed to evaluate elastomer deformations, it is not necessary to use any CAE package for structural analysis. However, an initial proposal for dynamic simulation using hyperelastic models through ANSYS software is also presented in this research. Validation of the results produced with the present methodology (mesh generation, flow simulation in metallic PCPs and simulation of fluid-structure interaction in elastomeric PCPs) is obtained through comparison with experimental results reported by the literature. It is expected that the development and application of such a computational model may provide better details of the dynamics of the flow within metallic and elastomeric PCPs, so that better control systems may be implemented in the artificial elevation area by PCP

Sono e percepção visuoespacial em trabalhadores de uma empresa petroquímica submetidos a esquemas de trabalho em turnos alternantes

Shift work consists of an array of unusual work hours, such as evenings and weekends, and increasing workload, in order to meet the uninterrupted production, which leads to changes in the quality, duration and regularity of sleep. Research indicates that sleep alteration cause cognitive processes to become slower, unstable and prone to errors, leading to loss of cognitive functions such as visuospatial perception. In this sense, this research aimed to evaluate sleep quality and its relation to visuospatial perception in workers in alternating shifts. Participants were 21 panel operators in a petrochemical company, male, aged 19-53 years. All participants were subjected to schedules of alternating shifts (day and night) of 12 nonstop hours and data were collected from 10 workers who were assigned to the day shift and 11 workers assigned to the night shift. For the sleep evaluation were used the Sleep Diary, the Sleep Habits Questionnaire, the Chronotype Identification Questionnaire and the Pittsburgh Sleep Quality Index (PSQI). The visuospatial skills were assessed using the Rey Complex Figure Test and attention was assessed using a portable version of the Psychomotor Vigilance Task (PVT). The results showed that the general sample of workers obtained poor sleep quality on working days and good sleep quality during the work break. There was shortened sleep duration in the work week and appropriate duration in the work break. No losses were found in the workers visuospatiality, but the good quality of sleep during the work break was correlated to adequate visuospatial performance, for the day shift workers. The attention performance oscillated throughout the work hours, especially on the night shift. It is concluded that the alternating shifts work scheme can be detrimental to the sleep quality workers and a good sleep quality can contribute to a better visuospatial performance

Estimação e compensação de não linearidades inerentes aos atuadores dos processos industriais

The oscillations presents in control loops can cause damages in petrochemical industry. Canceling, or even preventing such oscillations, would save up to large amount of dollars. Studies have identified that one of the causes of these oscillations are the nonlinearities present on industrial process actuators. This study has the objective to develop a methodology for removal of the harmful effects of nonlinearities. Will be proposed an parameter estimation method to Hammerstein model, whose nonlinearity is represented by dead-zone or backlash. The estimated parameters will be used to construct inverse models of compensation. A simulated level system was used as a test platform. The valve that controls inflow has a nonlinearity. Results and describing function analysis show an improvement on system response