1,721,008 research outputs found
Power amplifier ACPR simulation using standard Harmonic balance tools
No full textThe adoption of complex digital modulation techniques in wireless communication systems has posed a great demand on RF and microwave power amplifier performance. When high linearity is required, the amplifier characterization is based on intermodulation or, more commonly, on Adjacent Channel Power Ratio (ACPR) and other parameters more directly related to the actual circuit operation. In this paper a previously proposed Harmonic Balance (HB) algorithm is adopted for the ACPR simulation of power amplifiers excited by digitally modulated signals. With respect to other approaches the proposed technique provides fast and accurate results using a conventional HB engine without requiring special purpose algorithms
Multiband Multisine Excitation Signal for Online Impedance Spectroscopy of Battery Cells
Full text linkMultisine electrochemical impedance spectroscopy (EIS) represents a highly promising technique for the online characterization of battery functional states, offering the potential to monitor, in real-time, key degradation phenomena such as aging, internal resistance variation, and state of health (SoH) evolution. However, its widespread adoption in embedded systems is currently limited by the need to balance measurement accuracy with strict energy constraints and the requirement for short acquisition times. This work proposes a novel broadband EIS approach based on a multiband multisine excitation strategy in which the excitation signal spectrum is divided into multiple sub-bands that are sequentially explored. This enables the available energy to be concentrated on a limited portion of the spectrum at a time, thereby significantly improving the signal-to-noise ratio (SNR) without substantially increasing the total measurement time. The result is a more energy-efficient method that maintains high diagnostic precision. We further investigated the optimal design of these multiband multisine sequences, taking into account realistic constraints imposed by the sensing hardware such as limitations in excitation amplitude and noise level. The effectiveness of the proposed method was demonstrated within a comprehensive simulation framework implementing a complete impedance measurement system. Compared with conventional excitation techniques (i.e., the sine sweep and the classical single-band multisine methods), the proposed strategy is an optimal trade-off solution both in terms of energy efficiency and measurement time. Therefore, the technique is a valuable solution for real-time, embedded, and in situ battery diagnostics, with direct implications for the development of intelligent battery management systems (BMS), predictive maintenance, and enhanced safety in energy storage applications. © 2025 by the authors
A low-cost Electrochemical Impedance Spectroscopy-based sensor node for online battery cell monitoring
No full textThis paper proposes a proof-of-concept for a low-cost compact battery cell monitoring system based on Electrochemical Impedance Spectroscopy (EIS). The architecture exploits a multisine excitation signal, which reduces the time required for EIS measurement in the frequency range of interest, enabling online battery monitoring/diagnosis. A comprehensive CAD simulation of the system is performed in TINA-TI to evaluate its performance. The simulation covers the analysis of the general behaviour of the entire system and the complete signal elaboration flow, from analog signal processing to digital analysis of the impedance data based on Discrete Fourier Transform (DFT). This allowed for the analysis of the non-ideal effects of the components, as well as the error induced by the DFT algorithm. Moreover, thermal-noise limitation on the resolution of the system is assessed to verify its capability of detecting variations down to 1 mΩ. Finally, the system is tested in the reconstruction of the impedance spectrum of a battery cell described by an integer-order equivalent circuit model, demonstrating good accuracy. The overall system is realized with low-power off-the-shelf components, representing an innovative solution towards the feasibility of an even more integrated sensor node, which will be designed for implementation at cell level for in-operando sensing
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Automated Measurement Set-Up for the Electro-Mechanical Characterization of Piezoelectric Harvesters
Full text linkThis paper presents an automated measurement setup for the electro-mechanical characterization of piezoelectric energy harvesters in cantilever configuration. The setup provides a mechanical stimulus to the harvester and concurrently acquires mechanical and electrical quantities to characterize the electro-mechanical properties of the device under test in open-circuit conditions. The setup, composed by an electrodynamic shaker, a waveform analyzer, and two laser-based positioning sensors, is fully controlled via MATLAB. The use of two laser heads allows to measure the movement of the base, so to automatically consider artefacts due to the non-ideal response of the electrodynamic shaker. The proposed measurement system is compatible with any generic piezoelectric-cantilever harvesters, and it can be exploited for advanced modelling techniques that requires extensive experimental data. The proposed measurement setup was validated through the characterization of a commercial Piezo Protection Advantage (PPA) transducer up to 300 Hz
Experimental Demonstration of MASH Based Sigma Delta Radio over Fiber System for 5G C-RAN Downlink
Full text linkSigma Delta Radio over Fiber (S-DRoF) systems are looked upon as an enabling technology due to their advantages that comes due to combination of analog and digital radio over fiber (RoF) systems. In this paper, we have proposed and experimentally demonstrated a Multi-stAge-noise-SHaping (MASH) based Sigma Delta Modulated RoF system targeting 5G C-RAN (cloud/centralized radio access network) fronthaul applications. The evaluation has been done for LTE 20 MHz signal having 256 quadrature amplitude modulation with a carrier frequency of 3.5 GHz up to 5 Km of Standard Single Mode Fiber (SSMF). Furthermore, a comprehensive analysis of the design is explained followed by the experimental setup. The performance is reported in terms of error vector magnitude (EVM) and adjacent channel leakage ratio. It is concluded that S-DRoF substantiates the desired range of the 5G C-RAN fronthaul networks
- …
