{
  "abstract": "A stable inversion method is developed to reconstruct millimeter-scale solids-concentration profiles in particulate suspensions from monostatic sub-terahertz frequency-modulated continuous-wave (FMCW) radar measurements. In industrial particulate flows, cumulative attenuation renders the direct inversion of the path-integrated volume-scattering radar equation ill-conditioned. The method resolves this by an ensemble-averaged Mie-scattering closure coupled to a stable backward-integration scheme, yielding an analytical solution for the range-resolved solids concentration without case-specific parameter fitting against reference concentration measurements. The required range-dependent system response is determined by absolute near- and far-field calibration via external substitution with an electrically large metallic sphere. The method was evaluated against solids-volume-fraction estimates derived from differential-pressure measurements in a 3.1 m-tall circulating fluidized-bed riser operated with ambient air and copper powder (median diameter 32.6 $μ$m, density 8920 kg m$^{-3}$). The radar-derived and pressure-derived profiles agreed well across three superficial gas velocities producing distinct axial solids distributions, and the radar indicates sensitivity down to solids volume fractions of order $10^{-6}$.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.18567",
  "author_total": 7,
  "authors": [
    {
      "name": "Philip Kjaer Jepsen"
    },
    {
      "name": "Albert Monteith"
    },
    {
      "name": "Diana Carolina Guío-Pérez"
    },
    {
      "name": "Lars Ulander"
    },
    {
      "name": "Tomas Bryllert"
    },
    {
      "name": "Henrik Ström"
    },
    {
      "name": "David Pallarès"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/3wsh0g8wtbbx9.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.18567",
  "fulltext_url": null,
  "id": "3wsh0g8wtbbx9",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.18567",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "physics.ins-det"
    ],
    [
      "openalex",
      "2208|Terahertz technology and applications"
    ]
  ],
  "openalex": "W7213528876",
  "pdf_url": "https://arxiv.org/pdf/2609.18567",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-16",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/3wsh0g8wtbbx9.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:22:01Z",
      "native_id": "2609.18567",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.18567"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:physics.ins-det",
      "subfield": "applied-instrumentation"
    }
  ],
  "title": "Terahertz Radar Inversion for Range-Resolved Solids Concentration Profiling in Gas--Solid Flows",
  "title_text": "Terahertz Radar Inversion for Range-Resolved Solids Concentration Profiling in Gas--Solid Flows",
  "type": "preprint",
  "updated_at": "2026-10-30T12:22:01Z",
  "url": "https://research.draconitic.com/paper/3wsh0g8wtbbx9",
  "venue": "arXiv",
  "versions": []
}