Ethanol fuel analysis by time-domain reflectometry

The technique of Time Domain Reflectometry \ud (TDR) is applied for qualifying ethanol adulterated with water \ud and / or methanol. We used the commercial TDR model VG400, \ud which was originally developed for determining soil moisture, \ud making this study an original approach for qualifying fuels. \ud Several samples of alcohol with the addition of its main \ud contaminants (water and methanol) were prepared and \ud measured with the TDR sensor. The results indicate good \ud response linearity, showing the TDR technique is a promising \ud technique for fuel qualificatio

Silicon Field-Emission Devices Fabricated Using the Hydrogen Implantation-Porous Silicon (HI-PS) Micromachining Technique

This paper presents a relatively simple method to fabricate field-emitter arrays from silicon substrates. These devices are obtained from silicon micromachining by means of the HI-PS technique-a combination of hydrogen ion implantation and porous silicon used as sacrificial layer. Also, a new process sequence is proposed and implemented to fabricate self-aligned integrated field-emission devices based on this technique. Electrical characteristics of the microtips obtained show good agreement with the Fowler-Nordheim theory, which are suitable for the proposed application.Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq