Revista elektron

53-62

Authors: Pablo Tomás Bernadí, Pablo Gomez

This work describes an active noise control system implementation with reduced, low cost hardware using the EDU-CIAA-NXP board. The filtered-X LMS algorithm is described in its feedforward and feedback configurations, and design details for anti-alias and reconstruction filters are given. The software driving the system is described and test results in feedforward configuration are shown. Using a pure tone as the perturbing signal, a 30dB attenuation was achieved, which is adequate according to performance requirements in active noise control applications.

67-70

Authors: Eduardo Omar Acosta, María Teresa Garea, Natalia Álvarez, Liliana Perez

Lasers can operate in two regimes: continuous-wave mode or pulsed mode. In the simplest case, the former mode corresponds to monochromatic beams with Gaussian distribution of amplitudes (beam limited in space); whereas the latter mode corresponds to polychromatic beams with Gaussian distribution of frequencies (pulse limited in time). When the pulsed beams are reflected and refracted in different types of interfaces, they undergo peculiar distortions that bear some parallelism with those found for beams limited in space. These effects, as shown in a previous work, correspond to time delay (first order) and change of pulse width (second order). The distortions are clearly limited by the principle of causality and their interpretation, while not straightforward, emerges clearly when the associated fields are expressed in magnitude and phase. Since the analytical expressions are not simple even for the case where the pulse is transmitted through a single layer of linear, homogeneous, isotropic and transparent material, it makes it difficult to solve the inverse problem. In this work, we present an alternative analytical development that makes it possible to explicitly determine these distortion effects when a pulse impinges normally on a transparent isotropic layer immersed in a medium of analogous characteristics.

83-94

Authors: Joaquín Nacht, Mariana Falco, Gabriela Robiolo

Losses of time due to congestion and traffic jams are current events in cities due to a non-optimal configuration of the traffic lights. Various sciences and specialties have tried to understand the phenomenon and identify the causes in order to obtain an appropriate solution. The present work introduces the extension of a system oriented to agents whose purpose is to reduce the waiting time of the drivers in an intersection of streets; modelling now vehicles (cars and taxis), pedestrians and an intelligent traffic light that evaluates the weights of the flows in two directions (X and Y), turn left and right. For which, the validation was carried out in six possible scenarios, defined by means of the variation of the flow of vehicles and pedestrians, of a turning frequency in 20 and 80 and the application of different adjustment factors for intelligent traffic lights. The simulation environment was implemented in NetLogo, which allowed comparing the impact of the use of the intelligent traffic light versus a fixed-time traffic light. Finally, we will present the conclusions and future work.

101-106

Authors: Leonardo Martín Carducci, Ramiro Alonso, Walter Gustavo Fano

There are evidences in different parts of the world that suggest a relationship between certain types of magnetic phenomena at extremely low frequencies and the occurrence of a seismic event. To study these anomalies, it is essential to resort to more experimental evidence. Based on this motivation, this paper describes the implementation of a sensing station to record magnetic field emissions in the TLF-ELF bands, thus contributing to the study of its possible role as seismic precursors. The system also contemplates the sensing of some conventional precursors and other environmental parameters.

7-11

Authors: Carlos Carreño Romano, German Perez Fogwill, Guillermo D. Santiago, Martin G. Gonzalez

We present a new photoacoustic gas-trace measurement setup, based on a chirped optical chopper. This method combines features of the resonant and pulsed techniques. To show the advantages of this setup, we carried out a comparison with the resonant method in samples of NO2 contained in a one-dimensional acoustic resonator. The results show the chirped technique allows carrying out short-term acquisitions with good signal-to-noise ratio.

16-25

Authors: Liliana Inés Perez, Francisco Ezequiel Veiras

One of the most used tools in optics is ray tracing, due to the fact that is a fundamental tool for optic instruments design. In this work we analyze the successive deformations that both cylindrical and conical beams suffer when they impinge normal to a uniaxial crystal plane-parallel plate and go through the different interfaces. This is accomplished by following the path of each incident ray on the first interface. The ray tracing for the ordinary beam is the same as in isotropic media, but the extraordinary beam ray tracing is more difficult, for these rays are no longer contained in the incidence plane and their directions are different from those of the corresponding normals to the wavefront. We also analyze the loss of revolution symmetry of the beams and the image formation.

30-38

Authors: Inga Leonie Rittner, Walter Gustavo Fano

This article presents an implementation of the transmission/reflection line method to determine the intrinsic electromagnetic properties of unknown materials with relative magentic permeability not equal to one. With a vector network analyser (VNA) the forwardand back-scattered energy are measured to simultaneously extract the electric permittivity and magenetic permeability. The classic Nicolson-Ross-Weir extraction technique in frequency domain is explained in detail and presented such that the equations can be easily implemented by open-source post-processing with GNU Octave. The shift in phase reference planes and connector calibration measurements are performed such that a very low-cost VNA without de-embedding function can be used. A coaxial transmission line with N type female connectors is used providing a low-cost, easy to manufacture solution of a sample holder. The measurement procedure is valid from 2 MHz to 6 GHz, whereas the preliminary results are shown in the GHz range from 1 to 6 GHz. The article also comments on the sample preparation especially the thickness of the material slab.