A discrete-time approach to the steady-state and stability analysis of distributed nonlinear autonomous circuits

We present a direct method for the steady-state and stability analysis of autonomous circuits with transmission lines and generic non- linear elements. With the discretization of the equations that describe the circuit in the time domain, we obtain a nonlinear algebraic formulation where the unknowns to determine are the samples of the variables directly in the steady state, along with the oscillation period, the main unknown in autonomous circuits.An efficient scheme to buildtheJacobian matrix with exact partial derivatives with respect to the oscillation period and with re- spect to the samples of the unknowns is described. Without any modifica- tion in the analysis method, the stability of the solution can be computed a posteriori constructing an implicit map, where the last sample is viewed as a function of the previous samples. The application of this technique to the time-delayed Chua's circuit (TDCC) allows us to investigate the stability of the periodic solutions and to locate the period-doubling bifurcations.Peer ReviewedPostprint (published version

Steady state analysis of Chua's circuit with RLCG transmission line

In this paper we present a new technique to compute the steady state response of nonlinear autonomous circuits with RLCG transmission lines. Using multipoint Pade approximants, instead of the commonly used expansions around s=0 or s/spl rarr//spl infin/ accurate, low-order lumped equivalent circuits of the characteristic impedance and the exponential propagation function are obtained in an explicit way. Then, with the temporal discretization of the equations that describe the transformed circuit, we obtain a nonlinear algebraic formulation where the unknowns to be determined are the samples of the variables directly in the steady state, along with the oscillation period, the main unknown in autonomous circuits. An efficient scheme to build the Jacobian matrix with exact partial derivatives with respect to the oscillation period and with respect to the samples of the unknowns is obtained. Steady state solutions of the Chua's circuit with RLCG transmission line are computed for selected circuit parameters.Peer ReviewedPostprint (published version

Improving symbolic language comprehension

We focus on the goal of “Handling mathematical symbols and formalism” through the methodology of Content and Language Integrated Learning. The use of foreign language highlights, and possibly increases, the difficulties in the point of mathematical competence, but it can also be used to fix them. That is, making explicit the equivalence between formal and verbal language could improve symbolic language comprehension. Multilingual Formulae, an on -line resource at http://mformulae.epsem.upc.edu, is designed to give support in that direction, as equivalence is not found explicitly in textbooks or research papers. It contains sets of formulas with the corresponding written and oral version in several languages. The project, conducted by professors at the UPC Engineering School at Manresa Campus, is addressed to lecturers and students as a support to ensure effective communication when both Symbolic and Foreign language are used.Peer ReviewedPostprint (published version

Teaching symbolic language to non-native speakers

In this paper, we describe how an on-line resource, primarily intended to improve the proficiency in a foreign language, can also facilitate the understanding of the symbolic language in an engineering degree course. We think that thanks to the use of this resource, a course in an engineering degree can tackle both the challenge of teaching symbolic language to non-native speakers and the challenge of doing this without losing insight into the concepts that appear in the course.Postprint (published version

SNR measurement of superregenerative oscillators

© 2021 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.In this paper a method to measure the signal-to-noise ratio of superregenerative oscillators is presented. A spectrum analyzer can easily be coupled to a superregenerative oscillator without paying attention to possible loading effects. With just two measurements of the displayed power spectrum, in combination with the resolution bandwidth of the spectrum analyzer and the quench frequency of the oscillator, the signal-to-noise ratio is determined in a straightforward way. This is supported analytically with results from a frequency-domain analysis technique. Examples of the power displayed by a spectrum analyzer are given to provide insight into the explained procedure.Peer ReviewedPostprint (author's final draft

A discrete-time approach to the steady-state and stability analysis of distributed nonlinear autonomous circuits

We present a direct method for the steady-state and stability analysis of autonomous circuits with transmission lines and generic nonlinear elements. With the discretization of the equations that describe the circuit in the time domain, we obtain a nonlinear algebraic formulation where the unknowns to determine are the samples of the variables directly in the steady state, along with the oscillation period, the main unknown in autonomous circuits. An efficient scheme to build the Jacobian matrix with exact partial derivatives with respect to the oscillation period and with respect to the samples of the unknowns is described. Without any modification in the analysis method, the stability of the solution can be computed a posteriori constructing an implicit map, where the last sample is viewed as a function of the previous samples. The application of this technique to the time-delayed Chua's circuit (TDCC) allows us to investigate the stability of the periodic solutions and to locate the period-doubling bifurcations.Peer ReviewedPostprint (published version

A proof-of-concept superregenerative QPSK transceiver

In this paper we present a description and experimental verification of an HF-band proof-of-concept superregenerative transceiver for QPSK signals. We describe a simple implementation of an all-digital, FPGA-based, QPSK transmitter section. On the receiver side, the quench signal is generated in the same FPGA with a minimum of analog circuitry. As the main novelty, we present a simple synchronization scheme suitable for packetized transmissions.Peer ReviewedPostprint (author’s final draft

The nonlinear class-E amplifier: a case study of harmonic balance applied to switched circuits

Nonlinear switched circuits are usually analyzed in the time domain. The use of frequency-domain methods to analyze the steady-state of switched circuits is usually restricted to linear circuits and, although Volterra series approaches are applied to the distortion of nonlinear switched circuits, the use of harmonic balance (HB) methods in nonlinear switched circuits seems to be marginal if not discarded. In this paper, we analyze the nonlinear class-E amplifier with an ideal switch by means of the HB method. We show how the switching function may be carefully chosen to improve the accuracy of the solution. When the circuit achieves actual class-E operation, the method converges better and is more accurate than classical timedomain methods. We conclude that the HB method is an alternative to time-domain methods that can be used to analyze the class-E amplifier in its expected operation mode.Postprint (published version

Arduino-based low-cost device for the measurement of detonation times in blasting caps

The use of equipment such as oscilloscopes, high-speed cameras or acoustic sensors is quite common to measure detonation times from surface connectors and detonators. However, these solutions are expensive and, sometimes, not adequate to use in field conditions, such as mining or civil works. In this regard, a low-cost portable device is designed and tested using the Arduino platform, achieving a simple, robust and precise system to carry out field measurements. This study describes the characteristics and working principles of the designed device, as well as the verifications carried out to check the accuracy of the Arduino ceramic oscillator. Additionally, a field test was carried out using 100 actual detonators and surface connectors to verify the correct operation of the designed equipment. We have designed a device, and a methodology, to measure detonation instants with a minimum accuracy of 0.1 ms, being sufficient to carry out subsequent studies of detonation time dispersion for non-electric detonators.Peer ReviewedObjectius de Desenvolupament Sostenible::9 - Indústria, Innovació i InfraestructuraPostprint (published version

Class-talk: una guia de conversa per fer classes en una altra llengua

Una de les característiques de l’Espai Europeu d’Educació Superior és la mobilitat de l’estudiantat i el professorat, entre diferents universitats i països, i la impartició d’assignatures en una llengua estrangera (AICLE), per tal de millorar la competència lingüística, una de les competències genèriques escollides per la universitat. En aquest context, el portal web Class-Talk ofereix fraseologia habitual a la docència universitària, de manera que es converteix en una mena de guia de butxaca al servei de la comunitat universitària en pro del multilingüisme. Aquesta guia de conversa va ser elaborada de manera conjunta entre professorat de l’EPSEM i tècnics lingüistes del Servei de Llengües i Terminologia de la UPC. És un recurs d’accés obert en línea, que conté unes 600 entrades classificades segons el seu ús habitual en el desenvolupament d’una classe, al laboratori, als exàmens, etc. en català, castellà i anglès, amb fitxers àudio associats. En aquesta comunicació descriurem el seu contingut i com es pot utilitzar com a recurs per a impulsar la impartició de docència en una altra llengua, alimentant l’autoconfiança de professorat i estudiantat.Peer Reviewe