{
 "analysis": "Khafre Frequency Convergence Test",
 "version": "1.0",
 "status": "FROZEN",
 "frozen": "2026-08-17",
 "purpose": "Preserve the exact computational protocol that generated the first cross-survey robustness result, so later methodological improvements are compared against it rather than silently replacing it.",
 "dataset": {
  "name": "khafre-dimensional-provenance",
  "version": "1.1",
  "records": 246,
  "sha256": "9df5c41e678629ada7fcc9ec3a6f648fd32dea0ce0e3dc2731837a9bd65cc14d",
  "note": "Dataset is versioned independently of the analysis. Future dataset updates yield Analysis v1.1 (same protocol, new geometry); protocol changes yield v2.0."
 },
 "khafre_network_model": {
  "type": "1-D acoustic transmission-line network, complex ABCD matrices",
  "air": {
   "c_m_s": 343,
   "rho_kg_m3": 1.2,
   "loss_factor_eta": 0.015
  },
  "chambers": "lumped compliances C=V/(rho*c^2); burial chamber V=390 m3 default; subsidiary V=85 m3, toggle ON",
  "portcullis_states_default": "upper PARTIAL, lower PARTIAL (resistive constriction 3*rho*c/S)",
  "topology": "chamber - H3 - [coupling node] - H2 - J(lower branch: A1-Hs(subsidiary shunt mid)-portL-Dlow-open) - H1 - portU - Dup - open",
  "frequency_scan": {
   "fmin_hz": 0.4,
   "fmax_hz": 6.5,
   "points": 900
  },
  "peak_detection": "local maxima above max(0.15*global_max, 5*median)"
 },
 "geometry": {
  "presets": {
   "reconstruction": {
    "Dup": 32,
    "H1": 18,
    "H2": 22,
    "H3": 20,
    "Dlow": 34,
    "Hs": 16,
    "A1": 11,
    "status": "RECONSTRUCTION - envelope values, kept OUT of the historical ensemble"
   },
   "vyse_1837": {
    "Dup": 31.95,
    "H1": 18.06,
    "H2": 23.48,
    "H3": 15.65,
    "Dlow": 29.37,
    "Hs": 7.29,
    "A1": 5.64,
    "source": "Vyse 1840 vol.II pp.117-119, values read from page images"
   },
   "mr_tavole_1966": {
    "Dup": 31.7,
    "H1": 26.39,
    "H2": 23.61,
    "H3": 15.74,
    "Dlow": 34.15,
    "Hs": 15.75,
    "A1": 5.64,
    "source": "M&R Tavole TAV.7-10 dimension chains",
    "mapping_note": "H1 = L 8.07 + O 18.32; H2+H3 split G 39.35; A1 borrowed from Vyse (M&R give A in projection only) - the one non-M&R segment"
   }
  },
  "historical_ranges_HRANGE_m": {
   "Dup": [
    31.7,
    31.95
   ],
   "H1": [
    18.06,
    26.39
   ],
   "H2": [
    23.48,
    23.61
   ],
   "H3": [
    15.65,
    15.74
   ],
   "Dlow": [
    29.37,
    34.15
   ],
   "Hs": [
    7.29,
    15.75
   ],
   "A1": [
    5.64,
    5.64
   ]
  },
  "missing_measurements": "segment A (ascending) documented in neither tradition beyond horizontal projection - FIXED at Vyse-derived 5.64 m, stated",
  "disagreements": "carried as [min,max] ranges, never adjudicated; Dlow and Hs spreads partly reflect different datum points (recorded in dataset notes)"
 },
 "underground_model": {
  "status": "REPORTED / UNVERIFIED premise throughout",
  "shaft_length_m": 648,
  "shaft_diameter_m": 15,
  "shafts_parallel": 4,
  "chamber_volume_m3": 512000,
  "gas_fraction": 0.005,
  "gas_pressure_atm": 30,
  "top_boundary": "open (pressure release)",
  "wave_speed": "Wood's equation for gas-liquid mixture, rigid walls assumed",
  "underground_fundamental": "f_ug = c_eff/L at the default parameter set (c_eff ~786 m/s at defaults -> f_ug ~1.21 Hz)",
  "coupling": "single adjustable compliance standing in for the mechanical chain (fluid->wall->limestone->bedrock->foundation); strength 0.5 default; acknowledged crude - 3D elastodynamic FEM required for quantitative prediction",
  "shaft_count_claimed": 8,
  "topology_note": "CLAIM: 8 shafts, two rows of four, 4 converging into each of 2 ~80 m cubic chambers. MODEL B represents ONE symmetric group (4 parallel shafts -> 1 chamber), not 4 shafts total. Justification: for two identical uncoupled groups the modal frequencies are DEGENERATE, so a per-group model returns the same spectrum; cross-section affects impedance and chamber loading, not 1-D duct mode frequencies (f = n*c/2L). What the full 8/2 topology WOULD add: (a) symmetric/antisymmetric mode splitting IF the groups are coupled at top or bottom (nothing is claimed about any top connection), (b) roughly double the total volume velocity into bedrock - i.e. drive/coupling strength, not frequency, (c) the phase-symmetry families analyzed separately on the page. This labeling was ambiguous in v1.0 and is corrected here as documentation; no protocol numbers change.",
  "top_boundary_status": "UNKNOWN in the source claim - our own primary-source extraction recorded 'top connection: never described'. The 'open (pressure release)' setting is a stated MODEL ASSUMPTION, not a claim about the reported structures. Termination choice changes the entire modal family; this is the single largest free parameter in Model B."
 },
 "metric": "absolute distance |nearest peak of coupled spectrum - f_ug|, in Hz",
 "ensembles": {
  "A_primary_historical": {
   "n": 120,
   "procedure": "per-segment uniform sampling over HRANGE; all other parameters at defaults"
  },
  "B_randomized_control": {
   "n": 120,
   "procedure": "segment lengths randomized via exponential(1) weights normalized to preserve the 7-segment total length; minimum segment 4 m; topology, chamber connections and cross-section preserved",
   "preregistration": "specified before the cross-survey result was observed; NOT modified after observing the 88% result"
  },
  "reconstruction_marker": "single run at the reconstruction preset"
 },
 "outputs": [
  "median/mean/sd of A and B",
  "percentile = share of B with distance greater than median(A)",
  "distribution overlap = sum(min(histA,histB))/N over 30 bins to 1.5 Hz",
  "ensemble-A mode distribution over 40 additional samples"
 ],
 "randomness": {
  "seed": "NONE - browser Math.random(); results vary a few percent run to run",
  "reference_run": "2026-08-17: A median 0.34 Hz (sigma 0.01), B median 0.64 / mean 1.10 / sigma 1.08, reconstruction 0.43 Hz, percentile 88%, overlap 7%"
 },
 "interpretation": "Preliminary. The documented historical geometry produced a closer modal relationship to the reported underground fundamental than 88% of layouts generated by the specified randomized control. This is not evidence of intentional tuning; the null model and mechanical coupling approximation remain unresolved.",
 "note_on_live_page": "The page's sliders allow interactive exploration; v1.0 refers exclusively to the DEFAULT protocol above. Exploration is exploration, not the frozen analysis.",
 "amendment_log": [
  {
   "date": "2026-08-17",
   "type": "documentation only",
   "change": "Clarified shafts_parallel=4 as one of two symmetric claimed groups (8 claimed total) and elevated the unknown top boundary to an explicit named assumption. No parameter, code or result changed; v1.0 remains frozen."
  }
 ]
}