The purpose of this article is to present a sensitive optical system for immediate detection of traces of ammonia by means of photoacoustic spectroscopy and study some properties with both a pulsed CO2 laser (TEA) and a CW CO2 laser. The laser beam is aimed to an innovative dual resonator differential cell, which lowest resonant frequency is the first longitudinal mode at 1205 Hz, filled with a flowing NH3 and N2 mixture. The chosen cell’s material is polypropylene, suitable for reducing the effects of adsorption. As a result of physical adsorption-desorption studies, based on a pulsed CO2 laser, 5 % PA signal decay from an enclosed sample of 248 ppmV of NH3 in N2 is recorded within 1 hour. The setup for CW CO2 laser excitation takes advantage of a differential microphone connected to both resonators by picking up out of phase signals. For this purpose, the beam is modulated at the cell’s resonance by means of a chopper with a special blade which allows both reflection and transmission of the laser beam; the direct and the reflected beam are alternatively aimed to one resonator and the other. The measurements show that for the double resonator configuration a signal increase is achieved, as expected from the study of the sensitivity of both resonators separately, which have been previously characterized. Measurements with this system indicate a limit of detection of 13ppbV at the 10P(32) laser line, deduced from one standard deviation of the PA signal from pure N2.
KEYWORDS: Image processing, Mathematical morphology, Signal processing, Gallium arsenide, Video processing, Computer architecture, Real time image processing, Clocks, Video, Semiconductors
Mathematical Morphology appears as a theory that can solve some drawbacks of the classical lineal image processing. Linear filters generate a spatial distortion from initial image, what gives as a result that specific algorithms are usually needed for each process with a complexity that can not be implemented in VLSI systems for Real Time Image Processing. Mathematical Morphology is an alternative method to overcome the inherent drawbacks of the linear processing based on the comparison of an initial image with some well known geometric figures. In this paper we present the implementation of a specific processor that computes Mathematical Morphology (MM) basic operations. Using a clock frequency of 250 MHz this processor is able to handle real time 512x512 pixels video images. Mathematical Morphology allows the nonlinear processing of images and it is based on Dilation and Erosion operations using a geometric figure called Structural Elements (SE). More complex image processing can be performed using these basic operations. In this implementation the structural element of 3x3 pixels was chosen. 0.6micrometers HgaAsIV standard cells technology, from Vitesse Semiconductor Corporation, has been used achieving a logic level gate description with the possibility of migration to another technologies.
KEYWORDS: Asynchronous transfer mode, Transceivers, Clocks, Gallium arsenide, Logic, Standards development, Error control coding, Field effect transistors, Logic devices, System on a chip
This paper describes an ATM transceiver implementation with add/drop function over SDH (Synchronous Digital Hierarchy) able to handle STM-16c (OC-48c) signals. The design has been developed using Vitesse HGaAs-IV technology using DCFL (Direct Coupled FET Logic) standard cells and obtaining, in this way, a logic gate level description which could be easily exportable to any technology.
This paper presents a developed system for digitizing 3D objects in the footwear industry (e.g. mould, soles, heels) and their introduction in a CAD system for further manipulation and production of rapid prototypes. The system is based on the acquisition of the sequence of images of the projection of a laser line onto the 3D object when this is moving in front of the laser beam and the camera. This beam projection lights a 3D curve on the surface of the object, whose image is processed in order to obtain the 3D coordinates of every point of mentioned curve according to a previous calibration of the system. These coordinates of points in all the curves are analyzed and combined in order to make up a 3D wire-frame model of the object, which is introduced in a CAD station for further design and connection to the machinery for rapid prototyping.
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