Search results for "Boundary"

Nonlinear Nonhomogeneous Elliptic Problems

2019

We consider nonlinear elliptic equations driven by a nonhomogeneous differential operator plus an indefinite potential. The boundary condition is either Dirichlet or Robin (including as a special case the Neumann problem). First we present the corresponding regularity theory (up to the boundary). Then we develop the nonlinear maximum principle and present some important nonlinear strong comparison principles. Subsequently we see how these results together with variational methods, truncation and perturbation techniques, and Morse theory (critical groups) can be used to analyze different classes of elliptic equations. Special attention is given to (p, 2)-equations (these are equations driven…

Artificial neural network comparison for a SHM procedure applied to composite structures.

2013

In this paper different architectures of Artificial Neural Networks (ANNs) for structural damage detection are studied. The main objective is to create an ANN able to detect and localize damage without any prior knowledge on its characteristics so as to serve as a realtime data processor for SHM systems. Two different architectures are studied: the standard feed-forward Multi Layer Perceptron (MLP) and the Radial Basis Function (RBF) ANNs. The training data are given, in terms of a Damage Index ℑD, properly defined using the piezoelectric sensor signal output to obtain suitable information on the damage position and dimensions. The electromechanical response of the assembled structure has b…

Structures with Surface-Bonded PZT Piezoelectric Patches: a BEM Investigation into the Strain-transfer Mechanism for SHM applications

2009

In this work a three-dimensional BEM model is used for the analysis of structures with cracks and surface bonded piezoelectric PZT patches used as strain sensors. The cracked structure is modelled by the dual boundary element method, which allows for accurate and reliable crack analysis, while the piezoelectric patch is analyzed by a finite element state-space approach, that embodies both the full electro-mechanical coupling and the suitable sensor’s boundary conditions. The model is used to investigate the strain-transfer mechanism from an host elastic structure to the piezoelectric layer, taking into account the effect of the adhesive layer, as well as the mechanical interaction between t…

Numerical assessment of the thermomechanical behaviour of the DEMO Water-Cooled Lithium Lead inboard blanket equatorial module

2018

Abstract Within the framework of EUROfusion R&D activity, a research campaign has been carried out at the University of Palermo, in close cooperation with ENEA labs, in order to assess the thermo-mechanical performances of the DEMO Water-Cooled Lithium Lead (WCLL) inboard blanket equatorial module, whether properly integrated within its whole inboard segment. In particular, a detailed 3D model of this segment, including all the other modules, the back-supporting structure and the attachment system, has been considered in order to realistically simulate the boundary conditions affecting the equatorial module behaviour. The study has been focused on the investigation of the module thermo-mech…

Two non-zero solutions for Sturm–Liouville equations with mixed boundary conditions

2019

Abstract In this paper, we establish the existence of two non-zero solutions for a mixed boundary value problem with the Sturm–Liouville equation. The approach is based on a recent two critical point theorem.

Delineation of the boundary of an urban agglomeration: evidence from Riga, Latvia

2019

AbstractStatistical, morphological and functional approaches have long been used to delineate spatial boundaries of urban agglomerations. This research uses data from the Central Statistical Bureau and the State Revenue Service. The results indicate that morphological and functional approaches are essential when defining the agglomeration, however the outcomes are different. The most relevant consistency was observed in the territorial units adjoining the city of Riga due to the fact that they have a common labour market with Riga and share a strong functional linkage. However, the spatial extent based on the morphological approach confirms and highlights the effects of urban sprawl.

Radiative and dynamic effects of absorbing aerosol particles over the Pearl River Delta, China

2008

Abstract Results are reported from a ground-based measurement campaign conducted in a highly polluted region in southeast of China in October–November 2004. The experiment focused on absorbing aerosol particles and their effects on the solar radiation field and local meteorology. A Raman lidar in conjunction with Sun photometer data measured profiles of particle extinction; ground-based in situ data of aerosol optical properties were collected by nephelometer and absorption photometer. Exceptionally high values of aerosol optical depth of up to 1.5 were observed. The measurements were input to a radiative transfer model, which simulated high solar radiative forcing values for the aerosol pa…

Origin of high critical currents in YBa2Cu3O7−δ superconducting thin films

1999

Thin films of the high-temperature superconductor YBa2Cu3O7−δ exhibit both a large critical current (the superconducting current density generally lies between 1011 and 1012 A m−2 at 4.2 K in zero magnetic field) and a decrease in such currents with magnetic field that point to the importance of strong vortex pinning along extended defects1,2. But it has hitherto been unclear which types of defect—dislocations, grain boundaries, surface corrugations and anti-phase boundaries—are responsible. Here we make use of a sequential etching technique to address this question. We find that both edge and screw dislocations, which can be mapped quantitatively by this technique, are the linear defects t…

Thermomechanical Phenomena in Extended Thermodynamics of an Ideal Monoatomic Superfluid

1992

Surface Effects on Block Copolymer Melts Above the Order-Disorder Transition: Linear Theory of Equilibrium Properties and the Kinetics of Surface-Ind…

1997

A phenomenological theory is developed for static and dynamic aspects ofsurface- induced ordering of symmetrical block copolymers taking fluctuation corrections into account, but, considering conditions where the bulk block copolymer melt is still disordered, and a lin- earized version of the resulting Ginzburg-Landau type equation suffices. Both the semi-infinite geometry and symmetrical films of thickness 2L are treated, applying the same boundary con- ditions as used previously for a treatment of wetting in polymer blends, assuming short range surface forces and a long Wavelength approximation. For the static order parameter profile in thin film geometry, We derive an oscillatory converg…