Search results for "Method"
showing 10 items of 13253 documents
Boundary elements analysis of adhesively bonded piezoelectric active repair
2009
Abstract This paper presents the analysis of active piezoelectric patches for cracked structures by the boundary element method. A two-dimensional boundary integral formulation based on the multidomain technique is used to model cracks and to assemble the multi-layered piezoelectric patches to the host damaged structures. The fracture mechanics behavior of the repaired structures is analyzed for both perfect and imperfect interface between patches and host beams. The imperfect interface, representing the adhesive between two different layers, is modeled by using a “spring model” that involves linear relationships between the interface tractions, in normal and tangential directions, and the …
Numerical and experimental verification of a technique for locating a fatigue crack on beams vibrating under Gaussian excitation
2007
The stationary vibrations of a beam excited by Gaussian noise are strongly affected by the presence of a fatigue crack. Indeed, as soon as the crack arises the system response becomes non-linear due to crack breathing and a non-Gaussian behaviour is encountered. The paper presents both numerical and experimental investigations in order to assess the capability of the non-Gaussianity measures to detect crack presence and position. Monte Carlo method is applied to evaluate in time domain the higher order statistics of a cantilever beam modelled by finite elements. The skewness coefficient of the rotational degrees of freedom appears the most suitable quantity for identification purpose being …
Una propuesta sobre enseñanza de la relatividad en el bachillerato como motivación para el aprendizaje de la física
2007
Relativity is a very important part of modern physics. In this paper we analyze the teaching and learning of the theory of relativity in secondary education and we show some reasoned arguments against traditional methods to teach it. Finally, a didactic proposal for the teaching of relativity is presented; it comes as a conclusion that it is possible a suitable teaching of the principles of relative which should bring into the students a change in attitude, concepts and methodology.
The mixed capacitated general routing problem with turn penalties
2011
In this paper we deal with the mixed capacitated general routing problem with turn penalties. This problem generalizes many important arc and node routing problems, and it takes into account turn penalties and forbidden turns, which are crucial in many real-life applications, such as mail delivery, waste collection and street maintenance operations. Through a polynomial transformation of the considered problem into a Generalized Vehicle routing problem, we suggest a new approach for solving this new problem by transforming it into an Asymmetric Capacitated Vehicle routing problem. In this way, we can solve the new problem both optimally and heuristically using existing algorithms. A powerfu…
Isotropic-nematic interface in suspensions of hard rods: Mean-field properties and capillary waves
2006
We present a study of the isotropic-nematic interface in a system of hard spherocylinders. First we compare results from Monte Carlo simulations and Onsager density functional theory for the interfacial profiles of the orientational order parameter and the density. Those interfacial properties that are not affected by capillary waves are in good agreement, despite the fact that Onsager theory overestimates the coexistence densities. Then we show results of a Monte Carlo study of the capillary waves of the interface. In agreement with recent theoretical investigations (Eur.Phys.J. E {\bf 18} 407 (2005)) we find a strongly anistropic capillary wave spectrum. For the wave-numbers accessed in o…
Capillary Waves in a Colloid-Polymer Interface
2004
The structure and the statistical fluctuations of interfaces between coexisting phases in the Asakura-Oosawa (AO) model for a colloid--polymer mixture are analyzed by extensive Monte Carlo simulations. We make use of a recently developed grand canonical cluster move with an additional constraint stabilizing the existence of two interfaces in the (rectangular) box that is simulated. Choosing very large systems, of size LxLxD with L=60 and D=120, measured in units of the colloid radius, the spectrum of capillary wave-type interfacial excitations is analyzed in detail. The local position of the interface is defined in terms of a (local) Gibbs surface concept. For small wavevectors capillary wa…
Computer simulation studies of finite-size broadening of solid–liquid interfaces: from hard spheres to nickel
2009
Using Molecular Dynamics (MD) and Monte Carlo (MC) simulations interfacial properties of crystal-fluid interfaces are investigated for the hard sphere system and the one-component metallic system Ni (the latter modeled by a potential of the embedded atom type). Different local order parameters are considered to obtain order parameter profiles for systems where the crystal phase is in coexistence with the fluid phase, separated by interfaces with (100) orientation of the crystal. From these profiles, the mean-squared interfacial width w^2 is extracted as a function of system size. We rationalize the prediction of capillary wave theory that w^2 diverges logarithmically with the lateral size o…
On Science Museums, Science Capital, and the Public Understanding of Mathematical Modelling
2020
Students’ opportunities to learn informally (e.g. by watching documentaries, visiting museums) explain socio-economic inequities in school performances. To explore informal learning about mathematical modelling, I studied two science museums, as these are environments typically visited by middle-class families. I framed the study by using the notions science capital and the public understanding of mathematical modelling (PUMM) and explored how these are mediated in science museums. The research method entailed observations of displays, artefacts, and visitors. One science museum completely detached mathematics from its use value, whereas the other offered histories of how people used mathem…
Devenir chercheur ou enseignant chercheur : le goût pour la recherche des doctorants à l'épreuve du marché du travail
2016
Faire une thèse pour devenir chercheur ou enseignant-chercheur est souvent considéré comme un parcours difficile dont le résultat est incertain. Plus que dans d’autres pays, les diplômés de doctorat en France connaissent de fortes difficultés de stabilisation sur le marché du travail. Notre recherche s’interroge sur les raisons qui conduisent les jeunes à obtenir un doctorat puis à choisir une carrière de chercheur ou d’enseignant-chercheur et enfin, à s’y stabiliser. À partir d’une enquête du Céreq, nos résultats montrent que l’intérêt pour la recherche qu’ils ont manifesté dès le début des études supérieures et le capital social vont fortement structurer leur parcours universitaire et pro…
Impact of several histopathological prognosticators and local tumour extension on oncological outcome in pT3b/c N0M0 renal cell carcinoma.
2009
OBJECTIVE To investigate the prognostic relevance of different histopathological features and local tumour extension in patients with pT3b/c N0M0 renal cell carcinoma (RCC), as recently new proposals of reclassifying tumour fat invasion in pT3b/c RCC have been made but the effect of other histopathological tumour characteristics and combinations thereof with tumour invasion has yet to be determined in these patients. PATIENTS AND METHODS Between 1990 and 2006, 1943 patients underwent surgical treatment for renal tumours in our institution, of which 175 patients (8.7%) had pT3b/c RCC. After exclusion of 57 patients (32.6%) with lymph node and/or distant metastases at the time of diagnosis, 1…