{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,27]],"date-time":"2026-03-27T15:55:36Z","timestamp":1774626936154,"version":"3.50.1"},"reference-count":37,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2026,3,27]],"date-time":"2026-03-27T00:00:00Z","timestamp":1774569600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Life"],"abstract":"<jats:p>Current diagnostic assessments of lung disease rely primarily on medical imaging and global pulmonary function tests, which either provide static structural information or collapse complex regional behavior into global indices. As a result, important information about regional mechanical heterogeneity and early pathological changes may remain inaccessible. In this work, we introduce a conceptual diagnostic framework for the lung based on mechanical system identification and evaluate its feasibility using simulation-based analysis. Rather than directly imaging internal lung structure, the lung\u2013thorax system is treated as an identifiable viscoelastic dynamical system whose internal mechanical properties can be inferred from its response to controlled external excitation. A multi-degree-of-freedom mechanical representation of the lung was developed to capture the dominant low-frequency behavior of the chest wall and major lung regions. Sensitivity and Fisher-information analysis confirmed the structural identifiability of regional stiffness parameters (FIM eigenvalues \u03bb1 = 1.75 \u00d7 10\u22129 and \u03bb2 = 8.91 \u00d7 10\u221210). Inverse fitting experiments accurately recovered simulated stiffness perturbations (e.g., k01 = 240 \u2192 239.5; k02 = 154 \u2192 159.5) from noisy frequency response data, while classification experiments achieved the complete separation of simulated pathological configurations in an idealized synthetic scenario, supporting theoretical discriminability rather than clinical performance claims. These findings demonstrate the theoretical feasibility of a diagnostic paradigm in which regional lung mechanical alterations can in principle be identified through mechanical system identification rather than direct imaging, thereby suggesting a complementary approach for a non-invasive assessment of regional lung mechanics from externally measured responses. By quantifying regional stiffness and mechanical heterogeneity, this framework may also support the personalization and monitoring of pulmonary rehabilitation strategies in chronic respiratory disease.<\/jats:p>","DOI":"10.3390\/life16040555","type":"journal-article","created":{"date-parts":[[2026,3,27]],"date-time":"2026-03-27T14:33:33Z","timestamp":1774622013000},"page":"555","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["A Simulation-Based Mechanical System-Identification Framework for Non-Invasive Lung Diagnostics and Personalized Pulmonary Rehabilitation"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1789-4277","authenticated-orcid":false,"given":"Paraschiva","family":"Postolache","sequence":"first","affiliation":[{"name":"Faculty of Medicine, Grigore T. Popa University of Medicine and Pharmacy Iasi, 16 Universitatii Street, 700115 Iasi, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2791-3400","authenticated-orcid":false,"given":"C\u0103lin Gheorghe","family":"Buzea","sequence":"additional","affiliation":[{"name":"National Institute of Research and Development for Technical Physics, IFT Ia\u0219i, 700050 Iasi, Romania"},{"name":"\u201cProf. Dr. Nicolae Oblu\u201d Clinical Emergency Hospital Ia\u0219i, 700309 Iasi, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0024-0237","authenticated-orcid":false,"given":"Alin Horatiu","family":"Nedelcu","sequence":"additional","affiliation":[{"name":"Faculty of Medicine, Grigore T. Popa University of Medicine and Pharmacy Iasi, 16 Universitatii Street, 700115 Iasi, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Constantin","family":"Ghimus","sequence":"additional","affiliation":[{"name":"Faculty of Medicine, Grigore T. Popa University of Medicine and Pharmacy Iasi, 16 Universitatii Street, 700115 Iasi, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0000-3958-1090","authenticated-orcid":false,"given":"Valeriu Aurelian","family":"Chirica","sequence":"additional","affiliation":[{"name":"Faculty of Medicine, Grigore T. Popa University of Medicine and Pharmacy Iasi, 16 Universitatii Street, 700115 Iasi, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6325-7370","authenticated-orcid":false,"given":"Razvan Tudor","family":"Tepordei","sequence":"additional","affiliation":[{"name":"Faculty of Medicine, Grigore T. Popa University of Medicine and Pharmacy Iasi, 16 Universitatii Street, 700115 Iasi, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Simona Alice Partene","family":"Vicoleanu","sequence":"additional","affiliation":[{"name":"Faculty of Medicine, Grigore T. Popa University of Medicine and Pharmacy Iasi, 16 Universitatii Street, 700115 Iasi, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ana Maria","family":"Dumitrescu","sequence":"additional","affiliation":[{"name":"Faculty of Medicine, Grigore T. Popa University of Medicine and Pharmacy Iasi, 16 Universitatii Street, 700115 Iasi, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Manuela","family":"Ursaru","sequence":"additional","affiliation":[{"name":"Faculty of Medicine, Grigore T. Popa University of Medicine and Pharmacy Iasi, 16 Universitatii Street, 700115 Iasi, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8244-0522","authenticated-orcid":false,"given":"Emil","family":"Anton","sequence":"additional","affiliation":[{"name":"Faculty of Medicine, Grigore T. Popa University of Medicine and Pharmacy Iasi, 16 Universitatii Street, 700115 Iasi, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"C\u0103t\u0103lin Aurelian","family":"\u0218tef\u0103nescu","sequence":"additional","affiliation":[{"name":"Department of Sports and Physical Education, Faculty of Physical Education and Sport, \u201cDunarea de Jos\u201d University of Galati, 800008 Galati, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Constantin","family":"Stan","sequence":"additional","affiliation":[{"name":"Faculty of Medicine and Pharmacy, Research Centre in the Medical-Pharmaceutical Field, \u201cDunarea de Jos\u201d University of Galati, 800008 Galati, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sorin","family":"Bivolaru","sequence":"additional","affiliation":[{"name":"Medical Clinical Department, Faculty of Medicine and Pharmacy, \u201cDunarea de Jos\u201d University of Galati, 800008 Galati, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Alexandru","family":"Nechifor","sequence":"additional","affiliation":[{"name":"Department of Individual Sports and Physiotherapy, Faculty of Physical Education and Sport, \u201cDunarea de Jos\u201d University of Galati, 800008 Galati, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,3,27]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"319","DOI":"10.1183\/09031936.05.00034805","article-title":"Standardisation of spirometry","volume":"26","author":"Miller","year":"2005","journal-title":"Eur. 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