Optimizing Loudspeaker Performance Through Z-Domain Vector Fitting and Frequency-Warped Signal Processing Edgar B. Righi, Flavio A. M. Cipparrone, Phillip M. S. Burt IEEE Transactions on Audio Speech and Language Processing, 2026 Digital equalization is essential for correcting loudspeaker frequency responses in high-fidelity audio reproduction. Although infinite impulse response (IIR) filters are computationally efficient, conventional high-order design methods often lack perceptual relevance and may suffer from numerical instability. Warped IIR (WIIR) filters offer improved perceptual alignment, but robust high-order design remains challenging. This paper proposes a loudspeaker equalization methodology based on WIIR filters derived using the z-domain Vector Fitting (VFz) algorithm operating directly in a warped discrete-frequency domain. By integrating frequency warping into the fitting process, the proposed approach enables perceptually aligned modeling while preserving the numerical robustness and flexibility of VFz. The approach is validated through the design and real-time implementation of a high-order loudspeaker equalizer on a digital signal processor. Experimental results demonstrate sub-<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\text{0.1}\,\text{dB}$</tex-math></inline-formula> modeling accuracy and effective equalization performance across the audible range, providing an efficient solution for high-precision loudspeaker equalization in audio systems.
SUSTAINABLE PATHS: STRATEGIES FOR EFFICIENT ROUTES IN REDUCING FUEL CONSUMPTION AND POLLUTANT EMISSIONS IN SÃO PAULO Murilo Blasio, Flavio Cipparrone Proceedings of 2024 1st Edition of the Mediterranean Smart Cities Conference Mscc 2024, 2024 This study focuses on optimizing bus routes to reduce fuel consumption and emissions in São Paulo, using the Green Vehicle Routing Problem (GVRP) strategy. Three routes were analyzed, considering different vehicles and emission levels. Results indicate that the shortest route reduces CO2 emissions by 24%, while the fastest route decreases travel time by 60%. The replacement of Euro III vehicles with Euro VI stands out in pollutant reduction. The analysis weighs operational efficiency, passenger comfort, and sustainability, pointing to optimization opportunities in vehicle management and the adoption of more sustainable technologies in urban transportation.
Calculation of Step Discontinuities in Electric Circuits: A Time-Domain Analysis Flavio A. M. Cipparrone, Denise Consonni IEEE Transactions on Education, 2022 Contribution: Two general rules for calculating, in the time domain, step discontinuities of voltages and currents in electric circuits, combining physical principles and basic mathematical treatment. The two general rules, resulting from a formal method of analysis, provide a straightforward way to update the states of a circuit, immediately after the occurrence of switching or impulsive excitation. Among its advantages, they can be used to simplify the numerical simulation of elaborate circuit topologies by avoiding approximate models of impulsive sources or switches. Background: In most engineering undergraduate textbooks, the effects of switching and impulsive sources on higher order electric circuits are usually studied for the particular case of linear time-invariant (LTI) circuits in the Laplace transform domain. This approach, however, can be time consuming and demands little reasoning on the physical principles of circuit operation. Moreover, it is not adequate for linear time-variant or nonlinear circuits. Intended Outcomes: Step discontinuities in electric circuits, caused by switching or impulsive sources, are identified and calculated through the method, allowing complete responses to be obtained afterward. Not only can the method be extended to linear time-variant and nonlinear circuits but it also has interesting consequences in numerical simulation of circuits. Application Design: An application exercise and a set of conceptual questions on the subject were proposed to electrical engineering students. Findings: The analysis of the educational experiment indicates that applying the method presented herein improves the students’ ability to obtain initial conditions of circuits, being a more straightforward and effective approach than using Laplace transform techniques.
Modeling and Analysis of Inductive 'Kickback' in Low Voltage Circuits Flavio A. M. Cipparrone, Wesley Beccaro, Walter Kaiser IEEE Transactions on Education, 2020 Contribution: A didactic methodology, based on analytical expressions and experimental validation, to describe the process of abrupt current interruption in a series RL circuit, that considers real passive components and uses a toggle switch as disconnecting device. Background: In undergraduate courses, circuits adopted in transient analysis usually assume electrical switches in their ideal form, disregarding electrical impedance and its variation over time. Texts and instructors rarely point out these simplifications, so students can become confused. There is thus a need for a suitable switch model that yields a behavior consistent with real devices, while permitting a mathematical formulation of the inductor current. Intended Outcomes: That students should understand electrical component modeling, and how models can represent the physical phenomena that occur in electrical circuits. Application Design: An experiment, designed to evaluate students’ perceptions of switch modeling, modeled a switch by using three different equivalent circuits of increasing complexity, to allow a more realistic simulation. Electrical switch modeling is described, with the models being based on measurements performed on a real circuit. Findings: Student performance was evaluated qualitatively through test scores, and quantitatively through a post-class questionnaire. The results indicate that 96.15% of the students were able to propose an accurate model of the electrical switch.
Digital Image Inpainting by Estimating Wavelet Coefficient Decays from Regularity Property and Besov Spaces Sergio R. M. Penedo, Flavio A. M. Cipparrone, Joao F. Justo IEEE Access, 2019 Inpainting methods play a major role in image processing, minimizing the effects of data block loss in image transmission. They analyze primarily the spatial correlation between the portions of an image, usually without explicitly exploring information on the frequency domain. Techniques that evaluate losses of blocks in images do not locally describe a figure of merit for consistent measurement of spatial correlation between pixels of each corrupted block. This investigation presents a digital image inpainting technique, extensible to video applications, using the property of wavelet regularity in multiresolution image analysis, described locally in the sense of Besov vector spaces. Their generalized smoothness allows widespread changes in wavelet coefficients of image data, concealing errors in visual information. This technique estimates decay curves of wavelet coefficients from pixels, based in the observation of the regularity property, correcting pixel blocks contaminated by noise. This investigation proposes an algorithm in the wavelet transform domain, which detects and fixes damaged pixel blocks from a designed decay function for wavelet coefficients. Simulation results, obtained in corrupted images by several noise patterns, indicated better performance of this methodology when compared with other ones.
The chain rule applied to generalized functions for use in teaching electric circuits Flavio AM Cipparrone, Denise Consonni International Journal of Electrical Engineering and Education, 2017 Generalized functions, in particular the Heaviside unit step H( t) and the Dirac delta impulse δ( t), are valuable teaching tools in many contexts of electric circuits. However, engineering undergraduate courses and textbooks normally cover only an introduction to these functions along with their basic properties, without tackling the rigorous mathematical framework of the theory of distributions. In this work, the Heaviside function is used to represent a square wave signal f( t), and the Dirac function appears when the derivative is calculated. The steps for obtaining f ′( t) compare a graphical method with analytical procedures that employ the chain rule. The topic is further extended with the presentation of a theorem and a proposed corollary related to the study of the chain rule applied to general functions involving H( t) and δ( t). Thus, the work provides an appropriate mathematical support for the intuitive graphical method of analysis, which is very familiar in engineering practice.
A regularized robust design criterion for uncertain data A. H. Sayed, V. H. Nascimento, F. A. M. Cipparrone SIAM Journal on Matrix Analysis and Applications, 2002 This paper formulates and solves a robust criterion for least-squares designs in the presence of uncertain data. Compared with earlier studies, the proposed criterion incorporates simultaneously both regularization and weighting and applies to a large class of uncertainties. The solution method is based on reducing a vector optimization problem to an equivalent scalar minimization problem of a provably unimodal cost function, thus achieving considerable reduction in computational complexity.
Discussion of "enforcing passivity for admittance matrices approximated by rational functions" F.A.M. Cipparrone, B. Gustavsen, A. Semlyen, A. Feijoo, J. Cidras IEEE Transactions on Power Systems, 2001 The author discusses the paper "Enforcing passivity for admittance matrices approximated by rational functions" (see ibid., vol.16, no.1, p.97-104, 2001), requesting some additional information on the passivity enforcement of rational function approximations. The original authors' response is also included in this paper.
Automatic design of nonlinear filters by nearest neighbor learning IEEE International Conference on Image Processing, 1998
Optimization of the operational control in complex hydraulic systems Midwest Symposium on Circuits and Systems, 1995
RECENT SCHOLAR PUBLICATIONS
Optimizing Loudspeaker Performance Through Z-Domain Vector Fitting and Frequency-Warped Signal Processing EB Righi, FAM Cipparrone, PMS Burt IEEE Transactions on Audio, Speech and Language Processing , 2026 2026
Desenvolvimento e aplicação de um sistema eletrônico com arquitetura AUTOSAR para gerenciamento de motores à combustão interna MVL Rebolo, FAM Cipparrone 2026
Construção de Banco de Dados do Mercado Imobiliário. Um estudo na Cidade de São Paulo CGA Ribeiro, FF Helena, FAM Cipparrone Simpósio Brasileiro de Banco de Dados (SBBD), 354-359 , 2023 2023
Oportunidades no mercado imobiliário com aplicação de modelos de aprendizagem de máquina: um estudo de caso em São Paulo FF Helena Universidade de São Paulo , 2023 2023
Calculation of Step Discontinuities in Electric Circuits: A Time-Domain Analysis FAM Cipparrone, D Consonni IEEE Transactions on Education 65 (4), 575-583 , 2022 2022 Citations: 2
Modeling and Analysis of Inductive “Kickback” in Low Voltage Circuits FAM Cipparrone, W Beccaro, W Kaiser IEEE Transactions on Education 63 (1), 17-23 , 2019 2019 Citations: 4
Digital image inpainting by estimating wavelet coefficient decays from regularity property and Besov spaces SRM Penedo, FAM Cipparrone, JF Justo IEEE Access 7, 3459-3471 , 2018 2018 Citations: 4
The chain rule applied to generalized functions for use in teaching electric circuits FAM Cipparrone, D Consonni International Journal of Electrical Engineering Education 54 (3), 236-246 , 2017 2017 Citations: 3
Strategic implications of project portfolio selection G Vitolo, F Cipparrone Accounting & Taxation 6 (2) , 2014 2014 Citations: 2
Strategic implications of different criteria for project portfolio selection G Vitolo, F Cipparrone Global Conference On Business & Finance Proceedings 9 (1), 427 , 2014 2014 Citations: 4
Otimização linear robusta multitemporal de uma carteira de ativos com parâmetros de média e dispersão incertos AC Godói, FAM Cipparrone 2011
Construção de uma caixa acústica piramidal omnidirecional HV Jesus, TAB Rosa, FA João, G Stolfi, LAB Coelho, FAM Cipparrone 15 SIICUSP: anais , 2007 2007
Optimização organizacional na alocação de recursos financeiros e não financeiros: uma proposta pela análise por envoltória de dados AJ Jubran, FA de Magalhães Cipparrone, LMP Jubran Métodos numéricos en ingeniería, 2005: Granada, 2005, 439-439 , 2005 2005
Aplicação da análise por envoltória de dados: um estudo da eficiência das companhias seguradoras LMP Jubran, FAM Cipparrone 2005 Citations: 3
Método de refinamento hierárquico para solução de redes resistivas não lineares. AT Carvalho Universidade de São Paulo , 2005 2005
Cooperação de sistemas de distribuição de vapor a máquinas de papel baseada em previsão de demanda e controle operacional por sistemas fuzzy LS Medeiros Neto, FAM Cipparrone 2005
Controle ótimo de redes de adução de água baseado em programação linear seqüencial LFC Batista, FAM Cipparrone 2005
Cooperação de sistemas de distribuição de vapor a máquinas de papel baseada em previsão de demanda e controle operacional por sistemas fuzzy M Neto, L dos Santos, FAM Cipparrone 2005
A EFICIÊNCIA DAS OPERADORAS DE PLANOS DE SAÚDE NO BRASIL: Uma abordagem pela Aplicação da Análise Envoltória de Dados FA de Magalhães Cipparrone, LMP Jubran, AJ Jubran RETEC-Revista de Tecnologias 1 (1) , 2004 2004
Data mining na web AJ Jubran, LMP Jubran, FA de Magalhães Cipparrone, ... Escola Politécnica da Universidade de São Paulo (USP) , 2004 2004 Citations: 2
MOST CITED SCHOLAR PUBLICATIONS
A regularized robust design criterion for uncertain data AH Sayed, VH Nascimento, FAM Cipparrone SIAM Journal on Matrix Analysis and Applications 23 (4), 1120-1142 , 2002 2002 Citations: 109
Otimização do custo de transporte na distribuição-armazenagem de açúcar EC Colin, FAM Cipparrone, T Shimizu Production 9 (1), 23-30 , 1999 1999 Citations: 31
Technique for constructing grey-scale morphological operators using fuzzy expert system HY Kim, FAM Cipparrone, MTC Andrade Electronics Letters 33 (22), 1859-1861 , 1997 1997 Citations: 9
Discussion of" Enforcing passivity for admittance matrices approximated by rational functions" FAM Cipparrone, B Gustavsen, A Semlyen, A Feijoo, J Cidras IEEE Transactions on Power Systems 16 (4), 954-955 , 2001 2001 Citations: 5
Automatic design of nonlinear filters by nearest neighbor learning HY Kim, FAM Cipparrone Proceedings 1998 International Conference on Image Processing. ICIP98 (Cat … , 1998 1998 Citations: 5
Modeling and Analysis of Inductive “Kickback” in Low Voltage Circuits FAM Cipparrone, W Beccaro, W Kaiser IEEE Transactions on Education 63 (1), 17-23 , 2019 2019 Citations: 4
Digital image inpainting by estimating wavelet coefficient decays from regularity property and Besov spaces SRM Penedo, FAM Cipparrone, JF Justo IEEE Access 7, 3459-3471 , 2018 2018 Citations: 4
Strategic implications of different criteria for project portfolio selection G Vitolo, F Cipparrone Global Conference On Business & Finance Proceedings 9 (1), 427 , 2014 2014 Citations: 4
The chain rule applied to generalized functions for use in teaching electric circuits FAM Cipparrone, D Consonni International Journal of Electrical Engineering Education 54 (3), 236-246 , 2017 2017 Citations: 3
Aplicação da análise por envoltória de dados: um estudo da eficiência das companhias seguradoras LMP Jubran, FAM Cipparrone 2005 Citations: 3
Calculation of Step Discontinuities in Electric Circuits: A Time-Domain Analysis FAM Cipparrone, D Consonni IEEE Transactions on Education 65 (4), 575-583 , 2022 2022 Citations: 2
Strategic implications of project portfolio selection G Vitolo, F Cipparrone Accounting & Taxation 6 (2) , 2014 2014 Citations: 2
Data mining na web AJ Jubran, LMP Jubran, FA de Magalhães Cipparrone, ... Escola Politécnica da Universidade de São Paulo (USP) , 2004 2004 Citations: 2
Otimização por inteligência de enxames: algoritmos Ant Colony e Particle Swarm FK Grandi, FAM Cipparrone 2003 Citations: 2
Otimização do controle operacional de sistemas hidráulicos complexos FAM Cipparrone, JJ Cruz 1995 Citations: 2
Optimizing Loudspeaker Performance Through Z-Domain Vector Fitting and Frequency-Warped Signal Processing EB Righi, FAM Cipparrone, PMS Burt IEEE Transactions on Audio, Speech and Language Processing , 2026 2026
Desenvolvimento e aplicação de um sistema eletrônico com arquitetura AUTOSAR para gerenciamento de motores à combustão interna MVL Rebolo, FAM Cipparrone 2026
Construção de Banco de Dados do Mercado Imobiliário. Um estudo na Cidade de São Paulo CGA Ribeiro, FF Helena, FAM Cipparrone Simpósio Brasileiro de Banco de Dados (SBBD), 354-359 , 2023 2023
Oportunidades no mercado imobiliário com aplicação de modelos de aprendizagem de máquina: um estudo de caso em São Paulo FF Helena Universidade de São Paulo , 2023 2023
Otimização linear robusta multitemporal de uma carteira de ativos com parâmetros de média e dispersão incertos AC Godói, FAM Cipparrone 2011
