Results 31 to 40 of about 1,461,910 (180)
On analysis error covariances in variational data assimilation [PDF]
, 2008 The problem of variational data assimilation for a nonlinear evolution model is formulated as an optimal control problem to find the initial condition function (analysis).
Shutyaev, V. +2 more
core +2 more sources
Compact Manifolds With Unbounded Nilpotent Fundamental Groups and Positive Ricci Curvature
Communications on Pure and Applied Mathematics, EarlyView.ABSTRACT It follows from the work of Kapovitch and Wilking that a closed manifold with nonnegative Ricci curvature has a uniformly almost nilpotent fundamental group. Leftover questions and conjectures, have asked if in this context the fundamental group is actually uniformly almost abelian. The main goal of this work is to construct examples (Mk9,gk)$(
Elia Bruè, Aaron Naber, Daniele Semola
wiley +1 more source
Hessian-based response surface approximations for uncertainty quantification in large-scale statistical inverse problems, with applications to groundwater flow [PDF]
, 2013 textSubsurface flow phenomena characterize many important societal issues in energy and the environment. A key feature of these problems is that subsurface properties are uncertain, due to the sparsity of direct observations of the subsurface.
Flath, Hannah Pearl
core
Two Two‐Tier Stochastic Frontier Replications
Journal of Applied Econometrics, EarlyView.ABSTRACT We replicate the two foundational studies which proposed the two‐tier stochastic frontier model, first in the cross‐sectional setting and then for the fixed effects panel data model. We explore matters of software then and now, different mathematical formulations of the likelihood, and alternative current software tools.
Alecos Papadopoulos +1 more
wiley +1 more source
Mathematical Methods in the Applied Sciences, EarlyView.ABSTRACT This paper focuses on optimal design problems in the context of the Kirchhoff‐Love model for pure bending of a thin, solid, symmetric plate under a transverse load. The objective is to simultaneously determine the optimal outer shape of the domain and the distribution of two isotropic materials within the domain in order to minimize compliance.
Ivana Crnjac +2 more
wiley +1 more source
Segmentation of the retinal vasculature of the infant eye fundus: a comparison among vesselness measures [PDF]
, 2013 La Retinopatia del Prematuro (ROP) è una malattia grave che colpisce i bambini nati prematuri. I primi segnali del manifestarsi della malattia sono un'eccessiva tortuosità e dilatazione dei vasi della retina. Al giorno d'oggi, i clinici basano la propria
Gozzo, Alberto
core
An Adaptive Multiple Shooting Strategy for Optimal Control
Optimal Control Applications and Methods, EarlyView.We study how multiple shooting affects the convergence of Newton‐type methods for optimal control, comparing several shooting strategies across 40 benchmark problems. The study covers interior‐point and sequential quadratic programming methods with both Quasi‐Newton approximations and exact Hessians.
Robert Lampel, Sebastian Sager
wiley +1 more source
Dirichlet problem for degenerate Hessian quotient type curvature equations [PDF]
In the paper, we prove the existence and uniqueness results of the $C^{1,1}$ regular graphic hypersurface for Dirichlet problem of a class of degenerate Hessian quotient type curvature equations under the condition $\psi^{\frac{1}{k-l}}\in C^{1,1 ...
Chen, Xiaojuan, Xiang, Ni, Tu, Qiang
core +1 more source
New views of some invariants associated with the Cartesian 2D velocity gradient tensor
Quarterly Journal of the Royal Meteorological Society, EarlyView.Vorticity and divergence of horizontal flow are fundamental quantities in meteorology; both are linear functions of the four elements of the 2D velocity gradient tensor and both are formally unchanged under coordinate rotation. We explore four quadratic functions of the elements that are geometrically invariant in this sense, finding some novel ...
I. Roulstone, S. A. Clough, A. A. White
wiley +1 more source
The Pontryagin Forms of Hessian Manifolds [PDF]
, 2016 We show that Hessian manifolds of dimensions 4 and above must have vanishing Pontryagin forms. This gives a topological obstruction to the existence of Hessian metrics. We find an additional explicit curvature identity for Hessian 4-manifolds.
Armstrong, J.; id_orcid +3 more
core +1 more source