Study Of Design Parameters In Hydrogen Microsensors Integrated With Metal Semiconductor Nanoparticles

We investigated the effect of electrode design parameters on the performance of hydrogen microsensors. The sensors with varying electrode parameters were fabricated integrating micromachined interdigitated electrodes with indium oxide (In2O3) doped polycrystalline tin dioxide (SnO2) nanoparticles and tested in a controlled gas environment. It was observed that the sensitivity was closely related to the gap between, and a ratio of the gap to the width in interdigitated electrodes (IDE)

Study Of Design Parameters In Hydrogen Microsensors Integrated With Metal Semiconductor Nanoparticles

We investigated the effect of electrode design parameters on the performance of hydrogen microsensors. The sensors with varying electrode parameters were fabricated integrating micromachined interdigitated electrodes with indium oxide (In2O3) doped polycrystalline tin dioxide (SnO2) nanoparticles and tested in a controlled gas environment. It was observed that the sensitivity was closely related to the gap between, and a ratio of the gap to the width in interdigitated electrodes (IDE). Copyright © 2007 by ASME

Horizontal electric fields from lightning return strokes

Measurements are presented of simultaneous horizontal and vertical electric fields from 42 lightning return strokes in 27 flashes at distances from 7 to 43 km. The data were obtained at the NASA Kennedy Space Center, Florida, using an elevated spherical antenna having a system bandwidth of 3 Hz to 4 MHz. The strokes studied occurred in a 6-min interval from 1850 to 1856 UT on August 11, 1984. The 42 measured horizontal fields exhibited initial peaks having a mean half width of 0.52 μs. The ratio of the amplitude of the peak horizontal field to the associated vertical field peak had a mean value of 0.030, with a standard deviation of 0.007. The measured horizontal field wave shapes are compared with those obtained from calculations using the measured vertical fields and theory (the “wavetilt” formula) that models the fields as plane wave radiation over a homogeneous ground of uniform conductivity and permittivity. The local ground conductivity, measured as a function of depth using the Wenner four-probe method, was found to increase with depth within the region relevant to this study, from the surface to a depth of a few meters: the conductivity was 8.2×10−3 mho/m between the surface and a depth of 2.2 m, and 3.1×10−2 mho/m below this layer to a depth of 11 m. If a ground conductivity equal to that of the top layer is used in the wavetilt formula, the calculated horizontal field peaks are found to be, on average, about 33% wider and larger than the measured field peaks. Errors and compensation procedures for tilt of the spherical antenna, for electronic system distortion, and for electric field distortion at the antenna due to proximity of the ground and of the antenna support structure are described

Gestão de odores: fundamentos do Nariz Eletrônico Odor management: fundamentals of Electronic Nose

Narizes Eletrônicos têm sido desenvolvidos para detecção automática e classificação de odores, vapores e gases. São instrumentos capazes de medir a concentração ou intensidade odorante de modo similar a um olfatômetro, mas sem as limitações inerentes ao uso de painéis humanos, o que é altamente desejável. Um Nariz Eletrônico é geralmente composto por um sistema de sensores químicos e um sistema eletrônico associado à inteligência artificial para reconhecimento. Têm sido aplicados em muitas áreas, tais como análise de alimentos, controles ambientais e diagnósticos médicos. Do ponto de vista ambiental, sistemas de Narizes Eletrônicos vêm sendo usados para monitorar a qualidade do ar, detectar fontes e quantificar emissões odorantes. Este artigo pretende apresentar os fundamentos dos Narizes Eletrônicos.<br>Electronic noses have been developed for automatic detection and classification of odors, vapors and gases. They are instruments capable to identify odors as the human nose does, and measure the odor concentration or intensity according to similar metrics as an olfactometer, but without the inherent limitations of human panels. An Electronic Nose is generally composed of a matrix of chemical sensors and computer based system for odor recognition and classification. It has been applied in many areas, such as food quality analysis, explosives detection, environmental monitoring and medical diagnosis. In the ambient environment, systems of Electronic Noses have been used to monitor the quality of air and to detect and quantify odor sources and emissions. This article intends to present the fundamentals and main characteristics of Electronic Noses