Search results for " posterior"

A priori bounds and multiplicity of solutions for an indefinite elliptic problem with critical growth in the gradient

2019

Let $\Omega \subset \mathbb R^N$, $N \geq 2$, be a smooth bounded domain. We consider a boundary value problem of the form $$-\Delta u = c_{\lambda}(x) u + \mu(x) |\nabla u|^2 + h(x), \quad u \in H^1_0(\Omega)\cap L^{\infty}(\Omega)$$ where $c_{\lambda}$ depends on a parameter $\lambda \in \mathbb R$, the coefficients $c_{\lambda}$ and $h$ belong to $L^q(\Omega)$ with $q>N/2$ and $\mu \in L^{\infty}(\Omega)$. Under suitable assumptions, but without imposing a sign condition on any of these coefficients, we obtain an a priori upper bound on the solutions. Our proof relies on a new boundary weak Harnack inequality. This inequality, which is of independent interest, is established in the gener…

Maximal regularity via reverse Hölder inequalities for elliptic systems of n-Laplace type involving measures

2008

In this note, we consider the regularity of solutions of the nonlinear elliptic systems of n-Laplacian type involving measures, and prove that the gradients of the solutions are in the weak Lebesgue space Ln,∞. We also obtain the a priori global and local estimates for the Ln,∞-norm of the gradients of the solutions without using BMO-estimates. The proofs are based on a new lemma on the higher integrability of functions.

Toward a Quality Guide to Facilitate the Transference of Analytical Methods from Research to Testing Laboratories: A Case Study

2009

Abstract At present, there is no single viewpoint that defines QA strategies in analytical chemistry. On the other hand, there are no unique protocols defining a set of analytical tasks and decision criteria to be performed during the method development phase (e.g., by a single research laboratory) in order to facilitate the transference to the testing laboratories intending to adapt, validate, and routinely use this method. This study proposes general criteria, a priori valid for any developed method, recommended as a provisional quality guide containing the minimum internal tasks necessary to publish new analytical method results. As an application, the selection of some basic internal qu…

A local post-retrieval tool for satellite precipitation estimates

2012

As illustrated by several literature case studies spread around di erent geographic locations, satellite precipi- tation estimates, obtained by means of consolidated algorithms, often result being considerably biased. Moreover observed bias is related to geographic location since particular features such as latitude, presence of coastal areas and climatological and weather regime, a ect performances of satellite estimates. Bias adjusted products that make use of global ground-based precipitation estimates, are available as well but still these datasets may show a relevant bias level. In this study a procedure to bias-adjust satellite precipitation estimates has been devel- oped for the loca…

A Unified Approach to Measuring Accuracy of Error Indicators

2014

In this paper, we present a unified approach to error indication for elliptic boundary value problems. We introduce two different definitions of the accuracy (weak and strong) and show that various indicators result from one principal relation. In particular, this relation generates all the main types of error indicators, which have already gained high popularity in numerical practice. Also, we discuss some new forms of indicators that follow from a posteriori error majorants of the functional type and compare them with other indicators. Finally, we discuss another question related to accuracy of error indicators for problems with incompletely known data.

On the Difference between a-priori and observed statistical power - A comment on "statistical power and sample size calculations: A primer for pediat…

2019

Valutazione del legamento intermalleolare posteriore (LIMP) normale e patologico con RM dedicata da 1T (Orthone). Studio preliminare.

2007

OBIETTIVO: Identificare il legamento intermalleolare posteriore (LIMP) della caviglia in pazienti sani e con sindrome da impingement posteriore della caviglia mediante una macchina di RM dedicata ad alto campo (1T). MATERIALE E METODI: Sono stati rivalutati retrospettivamente 118 pazienti (68 maschi e 50 femmine; range di età: 11-78 anni; età media: 39 anni), sottoposti ad esame RM della caviglia con macchina RM dedicata da 1T (Orthone, Oni Medical Systerms) nel periodo maggio 2006 – gennaio 2007, in cui è stata acquisita almeno una scansione coronale (GE-2D o FSE-T2 pesata). RISULTATI: Il LIMP è stato identificato con certezza in 66 pazienti (59%) come una banda sottile o come due strisce …

Integration of onshore and offshore seismic arrays to study the seismicity of the Calabrian Region: a two steps automatic procedure for the identific…

2014

Abstract. We plan to deploy in the Taranto Gulf some Ocean Bottom broadband Seismometer with Hydrophones. Our aim is to investigate the offshore seismicity of the Sibari Gulf. The seismographic network optimization consists in the identification of the optimal sites for the installation of the offshore stations, which is a crucial factor for the success of the monitoring campaign. In this paper, we propose a two steps automatic procedure for the identification of the best stations geometry. In the first step, based on the application of a set of a priori criteria, the suitable sites to host the ocean bottom seismic stations are identified. In the second step, the network improvement is eval…

Computer-aided synthesis of complex pump and valve operations

1988

Abstract Process plant operators often have to synthesize sequences of valve and pump operations. On large plants there may be so many possible pipe routes and vessels that it is not practical to provide a priori computer support for every possible operation. The paper describes a program that could form the basis of an operator aid to synthesize appropriate operations from a knowledge of the plant layout and existing pumping operations. The paper concentrates on finding paths through the pipework and on generating a sequence of operations that establishes the path whilst simultaneously satisfying other safety and operating constraints. The paper includes two example problems which were use…

Guaranteed Error Bounds I

2014

In Chap. 3, we discussed the main ideas of fully reliable error control methods and the corresponding numerical algorithms with the paradigm of simple elliptic type problems. This chapter is intended to show a deep connection between a posteriori estimates of the functional type and physical relations generating the problem. Also, the goal of this chapter is to consider a wider set of problems arising in various applications and explain things in terms of computational mechanics. For this purpose, we begin with a simple class of mechanical problems (straight beams) and after that consider curvilinear beams and more complicated models of continuum mechanics (linear elasticity, viscous fluids…