Adaptive versus non-adaptive sampling for Gaussian-RBF surrogates: a replicated benchmark across analytical and differential-equation models
O. M. ShchepanchukMykhaylo Shcherbatyy
Sep 2026· Journal of Applied and Numerical Analysis· 0 citations
Abstract
Adaptive sampling extends a nested design point by point, but repeated
surrogate fitting and acquisition search are justified only when they improve prediction
or reduce expensive model evaluations. This paper presents a controlled, replicated
comparison of nine sampling strategies within a fixed Gaussian radial-basis-function
(RBF) pipeline and examines when sequential acquisition is justified.
Nine strategies—Random, Latin-hypercube sampling (LHS), scrambled Halton, sequential maximin, P-greedy, a nearest-neighbour leave-one-out (NN-LOO) proxy, a
β-NN-LOO/P proxy, and RBF criteria in the spirit of MEPE and EIGF—are compared
on seven analytical and differential-equation problem/QoI combinations: the smooth
analytic Branin function; a steady heat problem with a discontinuous conductivity
(Heat); an advection-dominated Graetz problem with a boundary layer (Graetz); and
a two-species reaction–diffusion system with two (2S-RD-2P) or four (2S-RD-4P) active parameters, each with a reaction-ODE functional ψ1 and a reaction–diffusion state
functional ψ2. Thirty design replications use a common 2000-point validation design. Supported endpoint improvements in the original adaptive-versus-static comparison require
agreement between Holm-adjusted permutation and paired Wilcoxon analyses; tolerance
performance combines attainment probability with the conditional first evaluated budget.
No strategy dominates within the tested suite and budgets. Geometry-retaining
adaptive criteria improve Heat, Graetz and both four-parameter 2S-RD QoIs, whereas
LHS remains effective on both two-parameter QoIs. Sequential maximin is best by
endpoint median on Branin and 2S-RD-4P/ψ2, second on 2S-RD-4P/ψ1, but eighth
on Graetz, so response-informed sampling does not uniformly dominate strong nested
geometry. Heat accuracy changes materially over εscore ∈ {0.5, 1, 2}, and fitting the
physical rather than logarithmic Heat target worsens every compared method’s physicalscale endpoint median. At Nc = 4000 the four-dimensional candidate pool is much
coarser than its two-dimensional counterpart; quadrupling the 2S-RD-4P pool gives
small, non-systematic endpoint shifts but less stable detailed rankings. The resulting
decision map is a scoped benchmark-based guide; its sensitivity to the scoring parameter,
fitted-target scale and finite candidate pool is stated explicitly.
This paper describes the formulation of a numerical model for simulating environmentally driven one-dimensional (1D) ground movements of expansive clay. The formulation is based on a finite-element model that simulates the redistribution of matric suction through a diffusion-type equation, explicitly accounting for volume changes due to wetting and drying of the clay. We synthesize and modify highly nonlinear constitutive relationships for (1) hysteretic soil water retention; (2) reversible soil shrinkage and expansion of clay; and (3) hydraulic conductivity, explicitly incorporating desiccation cracks through a multidomain framework and assuming a critical surface crack depth. These models are well-calibrated to published laboratory tests on a reference expansive clay, Denver bentonite. We demonstrate capabilities of the proposed formulation to simulate the response of a homogeneous expansive clay to periods of drying and wetting, considering the initial matric suction, saturated hydraulic conductivity of the intact clay, and critical crack depth as three primary sources of uncertainty. We compare ensemble model simulations with measured ground movements from an instrumented expansive clay test site in Texas over a 3-year period using detailed records of potential evapotranspiration and precipitation. By assigning weights to the ensemble simulations based on their performance, we constrain the ranges of the three key uncertain parameters. The results showed very reasonable first-order agreement with the measured data and highlight the potential of the proposed formulation. We anticipate that more reliable predictions can be achieved through direct measurements of actual in situ evaporation rates and local soil properties.
Mahdi Seyyedan, Jiali Ma, Ivo Rosa Montenegro et al.· Journal of Geotechnical and...· 1 citation
A rational design for next-generation thermo-responsive nanocarriers is proposed, in which polymer chemistry, nanoparticle structure, experimental characterization, and mechanistic modelling are integrated from the earliest stages of material development.
M. Schifone, Giuseppe Nunziata, Filippo Rossi· Advances in Colloid and Inte...· 1 citation
This paper develops the economics of artificial intelligence as a single connected structure, from the physics of the production function to the aggregate growth constraint and the valuation of the firms building and adopting it. Part I derives the cost of capability from scaling laws, shows why deployed models are systematically overtrained, and estimates the task-success slope directly from 23,235 public evaluation runs: $\hat\beta=0.83$ with no detectable release-date trend. Part II treats market structure: minimum efficient scale, the two-tier equilibrium in which open weights contest the trailing edge but never the frontier, and inference as a capacity-constrained short-run market that rations rather than prices. Part III is the core. We replace the standard automation assignment rule with one that prices reliability, obtaining an automation calendar $t_{\mathrm{aut}}=t_{1/2}+(\tau/\beta)\log_2\gamma$ in which verification cost, not task difficulty, sets the date; derive optimal checkpoint spacing $k^\star\approx\sqrt{v_{\mathrm{ver}}/\lambda}$; and prove the exact best-of-$k$ result. Against a sound verifier, sampling divides the reliability lag by $k$ in the small-$k$ regime and does better outside it; against an unsound verifier, it leaves an error floor that no amount of sampling removes. Part IV aggregates: diffusion inherits its time dispersion from verification costs, and revenue growth is governed by the density of tasks at the current threshold. Part V proves a Baumol bound --- with elasticity of substitution below one, aggregate growth converges to that of the least automatable essential input --- and states three jointly necessary conditions for explosive growth. Part VI treats measurement, policy, and financial markets. Part VII states the investment bridge: technological importance, industry profit, and security return are distinct objects, and a coherent valuation must respect the automation calendar, rent migration, capital consumption, and expectations already in price. The full valuation architecture is reserved for a separate companion paper. Part VIII states eighteen open problems.
Miquel Noguer Alonso· Zenodo (CERN European Organi...· 0 citations
A new method for surgically removing training examples from a model reveals that as datasets grow, the link between what a model learns and what it produces dissolves.