pith. machine review for the scientific record. sign in

arxiv: 2603.01359 · v2 · submitted 2026-03-02 · 📡 eess.SY · cs.SY· eess.SP

Recognition: no theorem link

Operational Modal Analysis of Aeronautical Structures via Tangential Interpolation

Gabriele Dessena , Marco Civera , Oscar E. Bonilla-Manrique
Authors on Pith no claims yet

Pith reviewed 2026-05-15 18:49 UTC · model grok-4.3

classification 📡 eess.SY cs.SYeess.SP
keywords operational modal analysisLoewner frameworktangential interpolationNExTaeronautical structuresmodal identificationstructural dynamicsimpulse response
0
0 comments X

The pith

Coupling NExT impulse responses with Loewner Framework tangential interpolation yields accurate modal parameters for aeronautical structures.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

This paper introduces the NExT-LF method for operational modal analysis of aeronautical structures. It retrieves impulse response functions via the Natural Excitation Technique and then uses the Loewner Framework to perform tangential interpolation in the frequency domain. The approach is positioned as a way to reduce the computational burden of Stochastic Subspace Identification on large systems and to improve noise handling compared with NExT-ERA. Experimental validation on a high-aspect-ratio wing spar and a helicopter rotor blade shows that the extracted modal parameters align closely with reference data, especially under high-amplitude excitation and in the lower frequency band.

Core claim

By combining the Natural Excitation Technique (NExT) to obtain impulse responses with the Loewner Framework (LF) using tangential interpolation, the NExT-LF approach produces modal parameters that align closely with experimental benchmark data for aeronautical structures, performing particularly well under high-amplitude conditions and in the low-frequency range.

What carries the argument

Tangential interpolation in the Loewner Framework, applied to frequency-domain representations of NExT-derived impulse responses, for efficient construction of reduced-order models and extraction of modal parameters.

If this is right

  • NExT-LF offers a computationally lighter alternative to SSI-based methods when the system size grows.
  • The method reduces sensitivity to measurement noise relative to direct NExT-ERA fitting in the reported tests.
  • Modal estimates remain consistent with experimental references on both a wing main spar and a bearingless rotor blade.
  • Strongest agreement occurs for high-amplitude excitations in the low-frequency portion of the spectrum.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The same impulse-response-plus-tangential-interpolation pipeline could be applied to output-only data from civil structures such as bridges or wind turbines.
  • If the interpolation step is made incremental, the approach might support near-real-time tracking of modal shifts for structural health monitoring.
  • Parameter-free scaling of the method to higher numbers of sensors would follow directly from the matrix-pencil construction inside the Loewner step.

Load-bearing premise

The impulse responses recovered by NExT remain sufficiently clean for the Loewner Framework's tangential interpolation to accurately extract modal parameters from the noisy aeronautical test data.

What would settle it

If NExT-LF applied to low-amplitude test data produces modal parameters that deviate substantially from the same benchmark references used in the high-amplitude cases, the claim of reliable performance across typical noise levels would be falsified.

Figures

Figures reproduced from arXiv: 2603.01359 by Gabriele Dessena, Marco Civera, Oscar E. Bonilla-Manrique.

Figure 1
Figure 1. Figure 1: NExT-LF workflow. featuring a more slender, higher-aspect-ratio wing with the same wing loading and a cruise condition of M = 0.6, intended to reflect an efficient turboprop configuration. An eXergy￾based optimisation yields a full-scale wingspan of 48 m [48]. To ensure compatibility with the wind-tunnel facility, a geometric scaling factor of 16 is adopted. The scaling procedure relied on non-dimensionali… view at source ↗
Figure 2
Figure 2. Figure 2: XB-2 wing main spar geometrical characteristics and corresponding accelerometer locations ( ). The odd-numbered accelerometers are positioned on the positive z side, whereas the even￾numbered sensors are mounted on the negative z side (retrieved from [49]). The experimental dataset employed in this work is sourced from [32] 1 , which also reports benchmark EMA results. The spar is excited for 20 m using a … view at source ↗
Figure 3
Figure 3. Figure 3: PSDs of the eight acceleration response channels measured on the XB-2 wing main spar (retrieved from [49]). As indicated by [PITH_FULL_IMAGE:figures/full_fig_p010_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: Equivalent FRFs obtained from the NExT-derived IRF of the XB-2 wing spar. (a) to (h) show the FRFs obtained, respectively, by setting output channel signals 1 to 8 the reference signal for NExT. retain only stable modes. The range of k was chosen to obtain a comparable count of stable modes between the methods. As discussed later, this condition could not be met for ERA. The stability assessment considers … view at source ↗
Figure 5
Figure 5. Figure 5: Stabilisation diagrams obtained using NExT-LF (a), NExT-ERA (b), and SSI (c) for the modal identification of the XB-2 wing spar (retrieved from [49]). damping. This behaviour is consistent with the identified values of ωn and ζn reported in Tables 1 and 2, respectively [PITH_FULL_IMAGE:figures/full_fig_p012_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: ϕn of the XB-2 wing spar identified using the output-only methods, overlaid with the benchmark results (retrieved from [49]). 4. Airbus Helicopters H135 Bearingless Main Rotor Blade In order to generalise the findings of the previous sections, a second benchmark aeronautical structure should be considered. For this aim, an Airbus Helicopters H135 BMR blade is chosen. The Airbus Helicopters H135, shown in … view at source ↗
Figure 7
Figure 7. Figure 7: (a) Airbus Helicopters H135 helicopter in Western Counties Air Operations Unit livery (UK – retrieved from [54]) and (b) the test setup of the ambient vibration testing on the Airbus Helicopter H135 BMR blade (adapted from [33]). The AVT was carried out in the aeroelastic laboratory of the Sir Peter Gregson Aerospace Integration Research Centre at Cranfield University, under controlled tem￾perature and hum… view at source ↗
Figure 8
Figure 8. Figure 8: Sensors layout of the instrumented Airbus Helicopter H135 BMR blade: A9-6 PCB Model 356B18 ( ), A5-3 PCB Model 356A16 ( ), and A2-1 PCB Model 356A45 ( ). Note that the z-axis is positive in the out-of-page direction. 18 acceleration time series are recorded from the 9 accelerometers at a sampling frequency fs = 2560 Hz for 600 s, using a similar setup to what is described for the XB-2 spar in Section 3, in… view at source ↗
Figure 9
Figure 9. Figure 9: PSDs and ANPSD from the signals recorded from accelerometers A1-9 on the Airbus Helicopter H135 BMR blade. As is clear from [PITH_FULL_IMAGE:figures/full_fig_p015_9.png] view at source ↗
Figure 10
Figure 10. Figure 10: Stabilisation diagrams superimposed on the ANPSD and obtained using NExT–LF (a), NExT–ERA (b), and SSI (c) for the modal identification of the Airbus Helicopters H135 BMR blade [PITH_FULL_IMAGE:figures/full_fig_p016_10.png] view at source ↗
Figure 11
Figure 11. Figure 11: The 14 ϕn (a-n) identified from the Airbus Helicopters H135 BMR blade AVT. https://doi.org/10.3390/aerospace1010000 [PITH_FULL_IMAGE:figures/full_fig_p019_11.png] view at source ↗
read the original abstract

Over the last decades, progress in modal analysis has enabled increasingly routine use of modal parameters for applications such as structural health monitoring and finite element model updating. For output-only identification, or Operational Modal Analysis (OMA), widely adopted approaches include Stochastic Subspace Identification (SSI) methods and the Natural Excitation Technique combined with the Eigensystem Realization Algorithm (NExT-ERA). Nevertheless, SSI-based techniques may become cumbersome on large systems, while NExT-ERA fitting can struggle when measurements are contaminated by noise. To alleviate these, this work investigates an OMA frequency-domain formulation for aeronautical structures by coupling the Loewner Framework (LF) with NExT, yielding the proposed NExT-LF method. The method exploits the computational efficiency of LF, due to the effectiveness of tangential interpolation, together with the impulse response function retrieval enabled by NExT. NExT-LF is assessed on two experimental benchmarks: the eXperimental BeaRDS 2 high-aspect-ratio wing main spar and an Airbus Helicopters H135 bearingless main rotor blade. The identified modal parameters are compared against available experimental references and results obtained via SSI with Canonical Variate Analysis and NExT-ERA. The results show that the modes identified by NExT-LF correlate well with benchmark data, particularly for high-amplitude tests and in the low-frequency range.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

3 major / 2 minor

Summary. The paper proposes NExT-LF, coupling the Natural Excitation Technique for recovering impulse responses with the Loewner Framework's tangential interpolation for frequency-domain Operational Modal Analysis on aeronautical structures. It validates the approach on two experimental benchmarks (BeaRDS high-aspect-ratio wing spar and Airbus H135 rotor blade), reporting that identified modal parameters correlate well with references and outperform or match SSI-CVA and NExT-ERA, especially under high-amplitude low-frequency conditions.

Significance. If substantiated with quantitative metrics, the method offers a computationally efficient alternative for output-only modal identification in noisy aeroelastic data, exploiting LF's tangential interpolation to handle large systems where SSI becomes cumbersome. The direct experimental comparisons on real aeronautical hardware provide practical value for applications like structural health monitoring, though the absence of error quantification limits assessment of its advantages.

major comments (3)
  1. [Abstract and Results] Abstract and results sections: the central claim that 'modes identified by NExT-LF correlate well with benchmark data' lacks any quantitative metrics (e.g., natural frequency errors in Hz or %, damping ratio deviations, or MAC values), rendering the correlation statement qualitative and difficult to compare against SSI-CVA or NExT-ERA baselines.
  2. [Method and Experimental Validation] Method and experimental sections: no SNR quantification, noise-sensitivity study, or conditioning analysis of the Loewner matrices constructed from NExT impulse responses is provided, leaving the tangential interpolation step vulnerable to residual noise in the BeaRDS and H135 datasets and undermining the claim of robustness outside high-amplitude low-frequency regimes.
  3. [Results] Results section: the manuscript does not report how post-processing choices in NExT (averaging, windowing) or Loewner rank selection criteria affect pole/residue accuracy, nor does it compare the singular-value structure of the Loewner matrices against benchmark FRF data to confirm separation of system poles from noise.
minor comments (2)
  1. [Abstract] Abstract: consider including at least one quantitative performance indicator (e.g., average frequency error) to make the 'correlate well' statement more precise.
  2. [Method] Notation: ensure consistent use of symbols for impulse response functions recovered by NExT and the Loewner matrices throughout the text.

Simulated Author's Rebuttal

3 responses · 1 unresolved

We thank the referee for the detailed and constructive review. The comments highlight important aspects for strengthening the quantitative validation of NExT-LF. We address each major comment below and will revise the manuscript accordingly where feasible.

read point-by-point responses

  1. Referee: [Abstract and Results] Abstract and results sections: the central claim that 'modes identified by NExT-LF correlate well with benchmark data' lacks any quantitative metrics (e.g., natural frequency errors in Hz or %, damping ratio deviations, or MAC values), rendering the correlation statement qualitative and difficult to compare against SSI-CVA or NExT-ERA baselines.

    Authors: We agree that the correlation claims would be more convincing with explicit quantitative metrics. In the revised manuscript we will add tables in the results section that report natural-frequency percentage errors, damping-ratio deviations in percent, and MAC values for all modes identified by NExT-LF, SSI-CVA and NExT-ERA against the available experimental references. These metrics will be computed from the same modal-parameter sets already obtained in the study. revision: yes

  2. Referee: [Method and Experimental Validation] Method and experimental sections: no SNR quantification, noise-sensitivity study, or conditioning analysis of the Loewner matrices constructed from NExT impulse responses is provided, leaving the tangential interpolation step vulnerable to residual noise in the BeaRDS and H135 datasets and undermining the claim of robustness outside high-amplitude low-frequency regimes.

    Authors: The original experimental campaigns did not record calibrated SNR values, so direct quantification from the raw data is not possible. We will nevertheless add a dedicated noise-sensitivity subsection that injects controlled Gaussian noise into the NExT-derived impulse responses at several SNR levels and tracks the resulting variation in identified poles and residues. We will also report the 2-norm condition numbers of the Loewner matrices and the decay of their singular values to document numerical robustness. revision: partial

  3. Referee: [Results] Results section: the manuscript does not report how post-processing choices in NExT (averaging, windowing) or Loewner rank selection criteria affect pole/residue accuracy, nor does it compare the singular-value structure of the Loewner matrices against benchmark FRF data to confirm separation of system poles from noise.

    Authors: We will expand the results section with a parametric study showing the effect of NExT averaging count and window type on pole accuracy (via frequency and damping errors). Loewner rank selection will be made explicit (singular-value threshold) and accompanied by singular-value plots. Because the experiments are strictly output-only, benchmark FRF data do not exist; we will instead compare the Loewner singular-value spectra to those obtained directly from the NExT impulse-response matrices to illustrate signal-noise separation. revision: partial

standing simulated objections not resolved
  • Direct comparison of Loewner singular-value structure against benchmark FRF data, which is unavailable because the validation relies exclusively on output-only experimental measurements.

Circularity Check

0 steps flagged

No significant circularity; NExT-LF validation rests on independent experimental benchmarks

full rationale

The paper introduces NExT-LF by coupling the established Natural Excitation Technique (for impulse response recovery) with the Loewner Framework (for tangential interpolation in the frequency domain). The central claim—that identified modes correlate well with benchmark data—is established through direct experimental comparison on the BeaRDS wing spar and H135 rotor blade against independent references and alternative methods (SSI-CVA, NExT-ERA). No derivation step reduces a prediction to a fitted input by construction, no self-citation chain bears the load of the result, and no ansatz or uniqueness theorem is smuggled in. The validation chain is externally falsifiable via the cited benchmark data and does not rely on internal re-use of fitted parameters.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

No explicit free parameters, new axioms, or invented entities are stated in the abstract; the work rests on standard OMA assumptions of linearity and stationarity.

axioms (1)
  • domain assumption The structure behaves as a linear time-invariant system during the measurement period.
    Standard premise underlying all OMA techniques referenced in the abstract.

pith-pipeline@v0.9.0 · 5556 in / 1153 out tokens · 23758 ms · 2026-05-15T18:49:12.177070+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Reference graph

Works this paper leans on

56 extracted references · 56 canonical work pages

  1. [1]

    Ewins, D.J.Modal Testing Theory, Practice and Application, 2nd ed.; Research Studies Press, 2000; p. 562

    work page 2000

  2. [2]

    Rainieri, C.; Fabbrocino, G.Operational Modal Analysis of Civil Engineering Structures; Springer New York, 2014; pp. 1–131. https://doi.org/10.1007/978-1-4939-0767-0. https://doi.org/10.3390/aerospace1010000 Version April 20, 2026 submitted toAerospace 22 of 25

    work page doi:10.1007/978-1-4939-0767-0 2014

  3. [3]

    System Identification Methods for (Operational) Modal Analysis: Review and Comparison.Archives of Computational Methods in Engineering2012,19, 51–124

    Reynders, E. System Identification Methods for (Operational) Modal Analysis: Review and Comparison.Archives of Computational Methods in Engineering2012,19, 51–124. https://doi.org/ 10.1007/s11831-012-9069-x

    work page doi:10.1007/s11831-012-9069-x

  4. [4]

    Dynamic investigation on the Mirandola bell tower in post-earthquake scenarios.Bulletin of Earthquake Engineering2017,15, 313–337

    Fragonara, L.Z.; Boscato, G.; Ceravolo, R.; Russo, S.; Ientile, S.; Pecorelli, M.L.; Quattrone, A. Dynamic investigation on the Mirandola bell tower in post-earthquake scenarios.Bulletin of Earthquake Engineering2017,15, 313–337. https://doi.org/10.1007/s10518-016-9970-z

    work page doi:10.1007/s10518-016-9970-z

  5. [6]

    Jelicic, G.; Schwochow, J.; Govers, Y.; Hebler, A.; Böswald, M. Real-time assessment of flutter stability based on automated output-only modal analysis.Proceedings of ISMA 2014 - International Conference on Noise and Vibration Engineering and USD 2014 - International Conference on Uncertainty in Structural Dynamics2014, pp. 3633–3646

    work page 2014

  6. [7]

    Sinske, J.; Govers, Y.; Jelicic, G.; Buchbach, R.; Schwochow, J.; Handojo, V .; Böswald, M.; Krüger, W.R. Flight testing using fast online aeroelastic identification techniques with DLR research aircraft HALO.17th International Forum on Aeroelasticity and Structural Dynamics, IFASD 2017 2017,2017-June

    work page 2017

  7. [8]

    In Sensors & Instrumentation and Aircraft/Aerospace Testing Techniques Vol

    Akers, J.C.; Winkel, J.P .; Chin, A.W.; Parks, R.A.; Chandler, D.E.; Stasiunas, E.C.; Allen, M.S., Operational Modal Analysis of the Artemis I Dynamic Rollout Test and Wet Dress Rehearsal. In Sensors & Instrumentation and Aircraft/Aerospace Testing Techniques Vol. 8; Walber, C.; Stefanski, M., Eds.; River Publishers, 2025; Vol. 8, pp. 91–112. https://doi....

    work page doi:10.1007/978-3-031-68188-2_10 2025

  8. [9]

    OMA analysis of a launcher under operational conditions with time-varying properties.CEAS Space Journal2018, 10, 381–406

    Eugeni, M.; Coppotelli, G.; Mastroddi, F.; Gaudenzi, P .; Muller, S.; Troclet, B. OMA analysis of a launcher under operational conditions with time-varying properties.CEAS Space Journal2018, 10, 381–406. https://doi.org/10.1007/s12567-018-0209-5

    work page doi:10.1007/s12567-018-0209-5

  9. [10]

    STARS missile – Modal analysis of first-flight data using the Natural Excitation Technique, NExT

    James, G.; Carne, T.; Edmunds, R. STARS missile – Modal analysis of first-flight data using the Natural Excitation Technique, NExT. In Proceedings of the Proc. SPIE Vol. 2251, Proceedings of the 12th International Modal Analysis Conference; DeMichele, D.J., Ed. Society for Experimental Mechanics, 1994. https://doi.org/10.2172/10113260

    work page doi:10.2172/10113260 1994

  10. [11]

    Ground vibration tests of a helicopter structure using OMA techniques.Mechanical Systems and Signal Processing2013,35, 35–51

    Ameri, N.; Grappasonni, C.; Coppotelli, G.; Ewins, D. Ground vibration tests of a helicopter structure using OMA techniques.Mechanical Systems and Signal Processing2013,35, 35–51. https://doi.org/10.1016/j.ymssp.2012.09.013

    work page doi:10.1016/j.ymssp.2012.09.013 2012

  11. [12]

    Automated Operational Modal Analysis of a Helicopter Blade with a Density-Based Cluster Algorithm.AIAA Journal2023,61, 1411–1427

    Sibille, L.; Civera, M.; Fragonara, L.Z.; Ceravolo, R. Automated Operational Modal Analysis of a Helicopter Blade with a Density-Based Cluster Algorithm.AIAA Journal2023,61, 1411–1427. https://doi.org/10.2514/1.J062084

    work page doi:10.2514/1.j062084

  12. [14]

    The Natural Excitation Technique (NExT) for Modal Parameter Extraction From Operating Wind Turbines

    III, G.H.J.; Carne, T.G.; Lauffer, J.P . The Natural Excitation Technique (NExT) for Modal Parameter Extraction From Operating Wind Turbines. Technical report, Sandia National Laboratories, 1993

    work page 1993

  13. [15]

    https: //doi.org/10.1007/978-1-4613-0465-4

    Overschee, P .V .; Moor, B.D.Subspace Identification for Linear Systems; Springer US, 1996. https: //doi.org/10.1007/978-1-4613-0465-4

    work page doi:10.1007/978-1-4613-0465-4 1996

  14. [16]

    Modal identification of output-only systems us- ing frequency domain decomposition.Smart Materials and Structures2001,10, 441–445

    Brincker, R.; Zhang, L.; Andersen, P . Modal identification of output-only systems us- ing frequency domain decomposition.Smart Materials and Structures2001,10, 441–445. https://doi.org/10.1088/0964-1726/10/3/303

    work page doi:10.1088/0964-1726/10/3/303

  15. [17]

    A robust probabilistic approach to stochastic subspace identification

    O’Connell, B.J.; Rogers, T.J. A robust probabilistic approach to stochastic subspace identification. Journal of Sound and Vibration2024,581, 118381. https://doi.org/10.1016/j.jsv.2024.118381

    work page doi:10.1016/j.jsv.2024.118381 2024

  16. [18]

    A new perspective on Bayesian operational modal analysis.Mechanical Systems and Signal Processing2025,236, 112949

    O’Connell, B.J.; Champneys, M.D.; Rogers, T.J. A new perspective on Bayesian operational modal analysis.Mechanical Systems and Signal Processing2025,236, 112949. https://doi.org/10 .1016/j.ymssp.2025.112949

    work page arXiv 2025

  17. [19]

    Amador, S.D.R.; Brincker, R. The new Subspace-based poly-reference Complex Frequency (S-pCF) for robust frequency-domain modal parameter estimation.Measurement: Journal of the International Measurement Confederation2024,225. https://doi.org/10.1016/j.measurement.2023 .113995. https://doi.org/10.3390/aerospace1010000 Version April 20, 2026 submitted toAero...

    work page doi:10.1016/j.measurement.2023 2023

  18. [20]

    Automatic identification of operational modal parameters for train suspension systems based on an improved SSI-FCM.Engineering Structures 2026,349, 121868

    Lv, L.; Hua, C.; Yu, H.; Dong, D.; Gong, C. Automatic identification of operational modal parameters for train suspension systems based on an improved SSI-FCM.Engineering Structures 2026,349, 121868. https://doi.org/10.1016/j.engstruct.2025.121868

    work page doi:10.1016/j.engstruct.2025.121868 2026

  19. [21]

    A novel approach for identifying system poles using multi-reference transmissibility functions based on frequency shifts.Journal of Sound and Vibration2026, 626, 119638

    Tarinejad, R.; Amanzad, F. A novel approach for identifying system poles using multi-reference transmissibility functions based on frequency shifts.Journal of Sound and Vibration2026, 626, 119638. https://doi.org/10.1016/j.jsv.2026.119638

    work page doi:10.1016/j.jsv.2026.119638 2026

  20. [22]

    Matthew Weinberg

    Wu, C.; He, S.; Yuan, B.; Yang, Z. An improved NExT-DMD for efficient automated operational modal analysis.Applied Mathematical Modelling2026,156, 116823. https://doi.org/10.1016/j. apm.2026.116823

    work page doi:10.1016/j 2026

  21. [23]

    Data-driven experimental modal analysis by Dynamic Mode Decomposition

    Saito, A.; Kuno, T. Data-driven experimental modal analysis by Dynamic Mode Decomposition. Journal of Sound and Vibration2020,481, 115434. https://doi.org/10.1016/j.jsv.2020.115434

    work page doi:10.1016/j.jsv.2020.115434 2020

  22. [24]

    Efficient modal parameter identification using DMD-DBSCAN and rank stabilization diagrams.Aerospace Science and Technology2025,161, 110112

    Wu, C.; Yang, Z.; He, S. Efficient modal parameter identification using DMD-DBSCAN and rank stabilization diagrams.Aerospace Science and Technology2025,161, 110112. https://doi. org/10.1016/j.ast.2025.110112

    work page doi:10.1016/j.ast.2025.110112 2025

  23. [25]

    Dynamic mode decomposition of numerical and experimental data.Journal of Fluid Mechanics2010,656, 5–28

    Schimid, P .J. Dynamic mode decomposition of numerical and experimental data.Journal of Fluid Mechanics2010,656, 5–28. https://doi.org/10.1017/S0022112010001217

    work page doi:10.1017/s0022112010001217

  24. [26]

    A machine learning approach for automatic operational modal analysis.Mechanical Systems and Signal Processing2022,170, 108813

    Mugnaini, V .; Fragonara, L.Z.; Civera, M. A machine learning approach for automatic operational modal analysis.Mechanical Systems and Signal Processing2022,170, 108813. https://doi.org/10.1016/j.ymssp.2022.108813

    work page doi:10.1016/j.ymssp.2022.108813 2022

  25. [27]

    Fully Automated Operational Modal Analysis using multi-stage clustering.Mechanical Systems and Signal Processing2017,84, 308–323

    Neu, E.; Janser, F.; Khatibi, A.A.; Orifici, A.C. Fully Automated Operational Modal Analysis using multi-stage clustering.Mechanical Systems and Signal Processing2017,84, 308–323. https: //doi.org/10.1016/j.ymssp.2016.07.031

    work page doi:10.1016/j.ymssp.2016.07.031 2016

  26. [28]

    A clustering-based strategy for automated structural modal identification.Structural Health Monitoring2018,17, 201–217

    de Almeida Cardoso, R.; Cury, A.; Barbosa, F. A clustering-based strategy for automated structural modal identification.Structural Health Monitoring2018,17, 201–217. https://doi.org/ 10.1177/1475921716689239

    work page doi:10.1177/1475921716689239

  27. [29]

    State of the Art in Automated Operational Modal Identification: Algorithms, Applications, and Future Perspectives.Machines2025,13, 39

    Mostafaei, H.; Ghamami, M. State of the Art in Automated Operational Modal Identification: Algorithms, Applications, and Future Perspectives.Machines2025,13, 39. https://doi.org/10.3 390/machines13010039

    work page

  28. [30]

    A Loewner-Based System Identification and Structural Health Monitoring Approach for Mechanical Systems

    Dessena, G.; Civera, M.; Fragonara, L.Z.; Ignatyev, D.I.; Whidborne, J.F. A Loewner-Based System Identification and Structural Health Monitoring Approach for Mechanical Systems. Structural Control and Health Monitoring2023,2023, 1–22. https://doi.org/10.1155/2023/18910 62

    work page doi:10.1155/2023/18910 2023

  29. [31]

    NExT-LF: A Novel Operational Modal Analysis Method via Tangential Interpolation.International Journal of Mechanical System Dynamics2025, 5, 401–414

    Dessena, G.; Civera, M.; Yousefi, A.; Surace, C. NExT-LF: A Novel Operational Modal Analysis Method via Tangential Interpolation.International Journal of Mechanical System Dynamics2025, 5, 401–414. https://doi.org/10.1002/msd2.70016

    work page doi:10.1002/msd2.70016

  30. [32]

    Ground vibration testing of a flexible wing: A benchmark and case study.Aerospace2022,9, 438

    Dessena, G.; Ignatyev, D.I.; Whidborne, J.F.; Pontillo, A.; Fragonara, L.Z. Ground vibration testing of a flexible wing: A benchmark and case study.Aerospace2022,9, 438. https://doi.org/ 10.3390/aerospace9080438

    work page doi:10.3390/aerospace9080438

  31. [33]

    Application of fibre optic sensing systems to measure rotor blade structural dynamics.Mechanical Systems and Signal Processing2021,158, 107758

    Weber, S.; Kissinger, T.; Chehura, E.; Staines, S.; Barrington, J.; Mullaney, K.; Fragonara, L.Z.; Petrunin, I.; James, S.; Lone, M.; et al. Application of fibre optic sensing systems to measure rotor blade structural dynamics.Mechanical Systems and Signal Processing2021,158, 107758. https://doi.org/10.1016/j.ymssp.2021.107758

    work page doi:10.1016/j.ymssp.2021.107758 2021

  32. [34]

    Modeling multi-port systems from frequency response data via tangential interpolation

    Lefteriu, S.; Antoulas, A.C. Modeling multi-port systems from frequency response data via tangential interpolation. In Proceedings of the 2009 IEEE Workshop on Signal Propagation on Interconnects, 5 2009, pp. 1–4. https://doi.org/10.1109/SPI.2009.5089847

    work page doi:10.1109/spi.2009.5089847 2009

  33. [35]

    A generalized state-space aeroservoelastic model based on tangential interpolation.Aerospace2019,6, 9

    Quero, D.; Vuillemin, P .; Poussot-Vassal, C. A generalized state-space aeroservoelastic model based on tangential interpolation.Aerospace2019,6, 9. https://doi.org/10.3390/aerospace601 0009

    work page doi:10.3390/aerospace601

  34. [36]

    Low-Order Parametric State-Space Modeling of MIMO Systems in the Loewner Framework.SIAM Journal on Applied Dynamical Systems2023,22, 3130–3164

    Vojkovic, T.; Quero, D.; Poussot-Vassal, C.; Vuillemin, P . Low-Order Parametric State-Space Modeling of MIMO Systems in the Loewner Framework.SIAM Journal on Applied Dynamical Systems2023,22, 3130–3164. https://doi.org/10.1137/22M1509898

    work page doi:10.1137/22m1509898

  35. [37]

    Improved tangential interpolation-based multi-input multi-output modal analysis of a full aircraft.European Journal of Mechanics - A/Solids2025,110, 105495

    Dessena, G.; Civera, M. Improved tangential interpolation-based multi-input multi-output modal analysis of a full aircraft.European Journal of Mechanics - A/Solids2025,110, 105495. https://doi.org/10.1016/j.euromechsol.2024.105495. https://doi.org/10.3390/aerospace1010000 Version April 20, 2026 submitted toAerospace 24 of 25

    work page doi:10.1016/j.euromechsol.2024.105495 2024

  36. [38]

    Multiple input tangential interpolation-driven damage detection of a jet trainer aircraft.Aerospace Science and Technology 2026,168, 111032

    Dessena, G.; Civera, M.; Marcos, A.; Chiaia, B.; Bonilla-Manrique, O.E. Multiple input tangential interpolation-driven damage detection of a jet trainer aircraft.Aerospace Science and Technology 2026,168, 111032. https://doi.org/10.1016/j.ast.2025.111032

    work page doi:10.1016/j.ast.2025.111032 2026

  37. [39]

    Damping Identification Sensitivity in Flutter Speed Estimation.Vibration2025,8, 24

    Dessena, G.; Pontillo, A.; Civera, M.; Ignatyev, D.I.; Whidborne, J.F.; Fragonara, L.Z. Damping Identification Sensitivity in Flutter Speed Estimation.Vibration2025,8, 24. https://doi.org/10 .3390/vibration8020024

    work page

  38. [40]

    Über monotone matrixfunktionen.Mathematische Zeitschrift1934,38, 177–216

    Löwner, K. Über monotone matrixfunktionen.Mathematische Zeitschrift1934,38, 177–216. https://doi.org/10.1007/BF01170633

    work page doi:10.1007/bf01170633

  39. [41]

    InModel Reduction and Approximation; Society for Industrial and Applied Mathematics, 2017; pp

    Antoulas, A.C.; Lefteriu, S.; Ionita, A.C., A Tutorial Introduction to the Loewner Framework for Model Reduction. InModel Reduction and Approximation; Society for Industrial and Applied Mathematics, 2017; pp. 335–376. https://doi.org/10.1137/1.9781611974829.ch8

    work page doi:10.1137/1.9781611974829.ch8 2017

  40. [42]

    A framework for the solution of the generalized realization problem

    Mayo, A.; Antoulas, A. A framework for the solution of the generalized realization problem. Linear Algebra and its Applications2007,425, 634–662. https://doi.org/10.1016/j.laa.2007.03.008

    work page doi:10.1016/j.laa.2007.03.008 2007

  41. [43]

    Tangential interpolation-based eigensystem realization algorithm for MIMO systems.Mathematical and Computer Modelling of Dynamical Systems2016,22, 282–306

    Kramer, B.; Gugercin, S. Tangential interpolation-based eigensystem realization algorithm for MIMO systems.Mathematical and Computer Modelling of Dynamical Systems2016,22, 282–306. https://doi.org/10.1080/13873954.2016.1198389

    work page doi:10.1080/13873954.2016.1198389 2016

  42. [44]

    A new approach to modeling multiport systems from frequency- domain data.IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems2010, 29, 14–27

    Lefteriu, S.; Antoulas, A.C. A new approach to modeling multiport systems from frequency- domain data.IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems2010, 29, 14–27. https://doi.org/10.1109/TCAD.2009.2034500

    work page doi:10.1109/tcad.2009.2034500 2009

  43. [45]

    Flexible High Aspect Ratio Wing: Low Cost Experimental Model and Computational Framework

    Pontillo, A.; Hayes, D.; Dussart, G.X.; Matos, G.E.L.; Carrizales, M.A.; Yusuf, S.Y.; Lone, M.M. Flexible High Aspect Ratio Wing: Low Cost Experimental Model and Computational Framework. In Proceedings of the 2018 AIAA Atmospheric Flight Mechanics Conference. American Institute of Aeronautics and Astronautics, 1 2018, pp. 1–15. https://doi.org/10.2514/ 6....

    work page 2018

  44. [46]

    Aeroelastic Scaling for Flexible High Aspect Ratio Wings

    Yusuf, S.Y.; Hayes, D.; Pontillo, A.; Carrizales, M.A.; Dussart, G.X.; Lone, M.M. Aeroelastic Scaling for Flexible High Aspect Ratio Wings. In Proceedings of the AIAA Scitech 2019 Forum. American Institute of Aeronautics and Astronautics, 1 2019, pp. 1–14. https://doi.org/10.2514/ 6.2019-1594

    work page 2019

  45. [47]

    High Aspect Ratio Wings on Commercial Aircraft: a Numerical and Experimental approach

    Pontillo, A. High Aspect Ratio Wings on Commercial Aircraft: a Numerical and Experimental approach. PhD thesis, Centre for Aeronautics, Cranfield University, 2020

    work page 2020

  46. [48]

    High aspect ratio wing design using the minimum exergy destruction principle

    Hayes, D.; Pontillo, A.; Yusuf, S.Y.; Lone, M.M.; Whidborne, J. High aspect ratio wing design using the minimum exergy destruction principle. In Proceedings of the AIAA Scitech 2019 Forum. American Institute of Aeronautics and Astronautics, 1 2019, p. 21. https://doi.org/10.2 514/6.2019-1592

    work page 2019

  47. [49]

    Tangential interpolation for the operational modal analysis of aeronautical structures

    Dessena, G.; Civera, M.; Bonilla-Manrique, O.E. Tangential interpolation for the operational modal analysis of aeronautical structures. In Proceedings of the 15th EASN International Conference, 14-17 of October 2025. In press, 2025, pp. 1–8

    work page 2025

  48. [50]

    Identification of Nonlinearity Sources in a Flexible Wing.Journal of Aerospace Engineering2025,38, 04025060

    Dessena, G.; Pontillo, A.; Ignatyev, D.I.; Whidborne, J.F.; Fragonara, L.Z. Identification of Nonlinearity Sources in a Flexible Wing.Journal of Aerospace Engineering2025,38, 04025060. https://doi.org/10.1061/JAEEEZ.ASENG-5508

    work page doi:10.1061/jaeeez.aseng-5508

  49. [51]

    Application of Damage Tolerance Principles for Improved Airworthiness of Rotorcraft

    Bansemir, H.; Emmerling, S. Fatigue Substantiation and Damage Tolerance Evaluation of Fiber Composite Helicopter Components. In Proceedings of the RTO AVT Specialists’ Meeting on "Application of Damage Tolerance Principles for Improved Airworthiness of Rotorcraft". NATO Research and Technology Organization, 1999. https://doi.org/10.14339/RTO-MP-024-ALL- PDF

    work page doi:10.14339/rto-mp-024-all- 1999

  50. [52]

    The EC135 - Applied Advanced Technology

    Bansemir, H.; Müller, R. The EC135 - Applied Advanced Technology. In Proceedings of the 53rd American Helicopter Society International Annual Forum 1997. American Helicopter Society International, 1997, pp. 846–861

    work page 1997

  51. [53]

    Aeromechanic Aspects in the Design of the EC135

    Kampa, K.; Enenkl, B.; Polz, G.; Roth, G. Aeromechanic Aspects in the Design of the EC135. Journal of the American Helicopter Society1999,44, 83–93. https://doi.org/10.4050/JAHS.44.83

    work page doi:10.4050/jahs.44.83

  52. [54]

    EC-135 – RIAT 2011

    Felce, T. EC-135 – RIAT 2011. Flickr, Inc. License: CC BY-SA 2.0 (https://creativecommons.org/ licenses/by-sa/2.0/). Source listed on page: Flickr photo ID 6199185182. https://www.flickr. com/photos/24874528@N04/6199185182/. https://doi.org/10.3390/aerospace1010000 Version April 20, 2026 submitted toAerospace 25 of 25

    work page doi:10.3390/aerospace1010000 2011

  53. [55]

    Caicedo, J. Practical Guidelines for the Natural Excitation Technique (NExT) and the Eigensys- tem Realization Algorithm (ERA) for Modal Identification Using Ambient Vibration.Experimen- tal Techniques2011,35, 52–58. https://doi.org/10.1111/j.1747-1567.2010.00643.x

    work page doi:10.1111/j.1747-1567.2010.00643.x 2010

  54. [56]

    Viscous damping identification in linear vibration.Journal of Sound and Vibration2007,303, 475–500

    Phani, A.S.; Woodhouse, J. Viscous damping identification in linear vibration.Journal of Sound and Vibration2007,303, 475–500. https://doi.org/10.1016/j.jsv.2006.12.031

    work page doi:10.1016/j.jsv.2006.12.031 2006

  55. [57]

    Novel LMD-NExT Hybrid Method for Damping Ratio Identification Under Sweep-Frequency Excitation.AIAA Journal2025, pp

    Zhu, R.; Wang, W.; Liu, Y.; Lei, M.; Fei, Q. Novel LMD-NExT Hybrid Method for Damping Ratio Identification Under Sweep-Frequency Excitation.AIAA Journal2025, pp. 1–8. https: //doi.org/10.2514/1.J066336

    work page doi:10.2514/1.j066336

  56. [58]

    https: //doi.org/10.1002/9781118535141

    Brincker, R.; Ventura, C.E.Introduction to Operational Modal Analysis; Wiley, 2015. https: //doi.org/10.1002/9781118535141. https://doi.org/10.3390/aerospace1010000

    work page doi:10.1002/9781118535141 2015