{"artifact_id":"L1-047","layer":"L1","title":"Elastography (Shear-Wave / Strain)","domain":"Medical Imaging","sub_domain":"Tissue stiffness imaging via shear waves or compression","physics_fingerprint":{"L_DAG":3.8,"title":"Elastography (Shear-Wave / Strain)","domain":"Medical Imaging","carrier":"acoustic","primitives":["L.shear_wave_excitation","L.wave_tracking","L.inverse_elasticity","int.temporal"],"sub_domain":"Tissue stiffness imaging via shear waves or compression","noise_model":"gaussian","problem_class":"nonlinear_inverse","solution_space":"2D_tissue_stiffness","difficulty_delta":5,"integration_axis":"temporal","sensing_mechanism":"shear_wave_elastography"},"observable_profile":{"metric":"PSNR_dB","regime":"Existence of the recovered 2D tissue stiffness is guaranteed within the declared Omega bounds. Uniqueness is local rather than global (non-convex landscape); convergence depends on initialisation and priors. Stability is moderately conditioned (kappa_eff ~= 15); wave_reflections dominates the stability cliff; tissue_anisotropy and the remaining mismatch parameters contribute higher-order bias terms. Additive gaussian thermal/electronic noise sets the irreducible data-fidelity floor, while mild Tikhonov or analytic inversion is sufficient at the nominal Omega point.","secondary":"SSIM"},"size_tiers":{"center_spec":{"omega":{"H":512,"W":512,"SNR_dB":22,"pre_load":0.0,"f_push_Hz":150,"N_time_samples":200,"wave_reflections":0.0,"tissue_anisotropy":0.0,"boundary_conditions":0.0},"input_format":"measurement_only","problem_class":"elastography","forward_operator":"elastography_forward","epsilon_fn_center":"20.0"},"omega_bounds":{"H":128,"W":128,"SNR_dB":[0.0,35.0],"pre_load":[0.0,0.3],"f_push_Hz":[30,500],"N_time_samples":[50,1000],"wave_reflections":[0.0,0.5],"tissue_anisotropy":[0.0,0.3],"boundary_conditions":[0.0,0.3]},"epsilon_bounds":{"psnr_db":[5.0,45.0]},"allowed_problem_classes":["elastography"],"allowed_omega_dimensions":["H","W","f_push_Hz","N_time_samples","SNR_dB","wave_reflections","tissue_anisotropy","pre_load","boundary_conditions","wave_reflections","tissue_anisotropy","pre_load","boundary_conditions"],"allowed_forward_operators":["elastography_forward"]},"hardness_fn":{"type":"epsilon_fn","delta":5,"kappa":300,"metric":"PSNR_dB"},"initiator_dataset":[{"name":"primary","weight":1.0,"ipfs_cid":null,"license_hash":null}],"status":"testnet","staked_pwm":0.0,"chain_hash":"0x32bfb5b1d5419d32c63af20f0085e7a909e469699d2554fbe22634cb5bdff4d6","chain_tx_hash":"0xcd2bd44cf717eb8346d81d901418c0f9a7781a3807e541b9dea512e9b8609912","chain_block":41553372}