Estruturação de um sistema de simulação de instrumentos de medição

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Tecnológico. Programa de Pós-Graduação em Engenharia MecânicaGarantir confiabilidade metrológica é uma necessidade nos sistemas da qualidade; avaliar incertezas de medições é imprescindível no processo de garantia da confiabilidade metrológica. A metodologia de avaliação de incertezas proposta pela ISO - International Organization for Standardization é a do "Guide to the Expression of Uncertainty in Measurement". Sua aplicação exige perfeita caracterização do processo metrológico e é bastante trabalhosa, mesmo que sejam poucos os instrumentos de medição envolvidos. Cada vez mais, os instrumentos são eletrônicos e modulares. Nas medições feitas com cadeias modulares, a caracterização dos processos requer conhecimentos simultâneos de metrologia e de instrumentação eletrônica. Nesses casos, a falta de pessoal especializado tem sido o maior fator limitante à obtenção da garantia da confiabilidade metrológica. A atividade experimental pode contribuir de forma muito significativa, tanto para se conhecer o comportamento metrológico de processos de medição quanto para formação de recursos humanos. Porém a experimentação, além de ter alto custo, esbarra na impossibilidade prática de variação controlada de muitos dos parâmetros envolvidos. Identifica-se aí um cenário apropriado para aplicação de simuladores. Neste trabalho está estruturado um sistema de simulação digital de instrumentos, congregando o estado-da-arte em metrologia, instrumentação, qualidade industrial e informática. O sistema consiste de ambientes, modelos e procedimentos de simulação direcionados à análise do comportamento metrológico de cadeias modulares de medição formadas por instrumentos elétricos. São propostas alternativas inéditas, empregadas no desenvolvimento em Labview de ambientes de simulação e de modelos de características metrológicas estáticas e dinâmicas

Desenvolvimento do sistema elétrico de um apalpador para medição tridimensional

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico.Programa de Pós-Graduação em Engenharia Elétrica

Comparison of Measurement Methods for Piston and Crankshaft Kinematics of Reciprocating Compressors

The measurement of the kinematics of reciprocating compressors, such as position, speed and acceleration, is an important part of a wide range of tests. Examples of these tests are the determination of the pV diagram, which depends on the measurement of the piston position; the determination of the Coefficient of Performance (COP), which requires the measurement of angular speed; friction loss experiments, which require the rotational speed and the deceleration of the compressor. Due to their importance for R&D of reciprocating compressors, this paper presents a review of the kinematic measuring methods for reciprocating compressors. Additionally, a test rig was designed to perform static and dynamic measurements of the piston and crankshaft kinematics. The applicability of a linear variable inductance transducer in a reciprocating compressor was evaluated by comparing its response to the measurements obtained from an encoder

Modeling Overdispersed Dengue Data via Poisson Inverse Gaussian Regression Model: A Case Study in the City of Campo Grande, MS, Brazil

Dengue fever is a tropical disease transmitted mainly by the female Aedes aegypti mosquito that affects millions of people every year. As there is still no safe and effective vaccine, currently the best way to prevent the disease is to control the proliferation of the transmitting mosquito. Since the proliferation and life cycle of the mosquito depend on environmental variables such as temperature and water availability, among others, statistical models are needed to understand the existing relationships between environmental variables and the recorded number of dengue cases and predict the number of cases for some future time interval. This prediction is of paramount importance for the establishment of control policies. In general, dengue-fever datasets contain the number of cases recorded periodically (in days, weeks, months or years). Since many dengue-fever datasets tend to be of the overdispersed, long-tail type, some common models like the Poisson regression model or negative binomial regression model are not adequate to model it. For this reason, in this paper we propose modeling a dengue-fever dataset by using a Poisson-inverse-Gaussian regression model. The main advantage of this model is that it adequately models overdispersed long-tailed data because it has a wider skewness range than the negative binomial distribution. We illustrate the application of this model in a real dataset and compare its performance to that of a negative binomial regression model

Isotope ratios of H, C, and O in CO2 and H2O of the Martian atmosphere

Stable isotope ratios of H, C, and O are powerful indicators of a wide variety of planetary geophysical processes, and for Mars they reveal the record of loss of its atmosphere and subsequent interactions with its surface such as carbonate formation. We report in situ measurements of the isotopic ratios of D/H and O-18/O-16 in water and C-13/C-12, O-18/O-16, O-17/O-16, and (CO)-C-13-O-18/(CO)-C-12-O-16 in carbon dioxide, made in the martian atmosphere at Gale Crater from the Curiosity rover using the Sample Analysis at Mars (SAM)'s tunable laser spectrometer (TLS). Comparison between our measurements in the modern atmosphere and those of martian meteorites such as ALH 84001 implies that the martian reservoirs of CO2 and H2O were largely established similar to 4 billion years ago, but that atmospheric loss or surface interaction may be still ongoing