Structural Health Monitoring of Composite Airframe

Seminario impartido por el Profesor Aliabadi para describir los últimos logros obtenidos en el seno de los grupos de investigación que dirige en el Imperial College de Londres.Design and maintenance of future airframe composite structures is mainly influenced by the requirement to cope with accidental impact damage. The impact detection and identification strategy for existing structures is of primary importance both in structural health monitoring (SHM) and in non-destructive evaluation (NDE) techniques. Accurately detecting and characterizing an impact event based on sensor data leads us towards condition-based monitoring (CBM), where the subsequent damage can then be detected through active sensing strategies. In this talk, SHM techniques based ultrasonic guided wave will be presented for both passive and active SHM system. Application of these methods to complex stiffened panel will be shown through both experimental measurements and finite element simulations.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

More analysts, better ratings: Do rating agencies invest enough in less developed countries?

Rating agencies' track record is good in developed countries but poor in emerging economies. Why? Given the almost-monopolistic structure of the industry, we conjecture that agencies might underinvest in information gathering. We propose an indicator quantifying the agencies' effort to gather information and assess whether greater effort affects rating levels. We detect: (i) absolute underinvestment for non-OECD sovereigns (less effort in spite of greater opaqueness); (ii) relative underinvestment for non-OECD firms compared with OECD ones (though the former receive a larger effort, more intense effort boosts firm ratings in non-OECD countries while depressing them in OECD countries).sovereign risk, credit ratings, rating agencies' effort

Factorization and escorting in the game-theoretical approach to non-extensive entropy measures

The game-theoretical approach to non-extensive entropy measures of statistical physics is based on an abstract measure of complexity from which the entropy measure is derived in a natural way. A wide class of possible complexity measures is considered and a property of factorization investigated. The property reflects a separation between the system being observed and the observer. Apparently, the property is also related to escorting. It is shown that only those complexity measures which are connected with Tsallis entropy have the factorization property.Comment: 7 pages, revtex4. For NEXT2005 proceeding

Expectations for a new calorimetric neutrino mass experiment

A large calorimetric neutrino mass experiment using thermal detectors is expected to play a crucial role in the challenge for directly assessing the neutrino mass. We discuss and compare here two approaches to the estimation of the experimental sensitivity of such an experiment. The first method uses an analytic formulation and allows to readily obtain a sensible estimate over a wide range of experimental configurations. The second method is based on a frequentist Montecarlo technique and is more precise and reliable. The Montecarlo approach is then exploited to study the main sources of systematic uncertainties peculiar to calorimetric experiments. Finally, the tools are applied to investigate the optimal experimental configuration for a calorimetric experiment with Rhenium based thermal detectors.Comment: 25 pagers, 16 figure

Effect of premixing quality on oxides of nitrogen in gas turbine combustors foi HC

Experiments were conducted to determine the effectiveness of several premixing prevaporizing gas turbine combustor designs in reducing formation of oxides of nitrogen at the supersonic cruise condition. An atomized spray from a single injector mounted on the axis of the mixer tube produced a high initial concentration of fuel near the axis and only moderate premixed conditions entering the combustor. A fuel spray produced by 12 flush-mounted normal injection orifices in the mixer tube wall produced a good initial despersion of fuel and resulted in nearly complete premixing. Oxides of nitrogen emission levels of the order of 0.2 g NO2/kg fuel were obtained at 99 percent combustion efficiency at an equivalence ratio of 0.4. Overall total pressure drop was less than 3 percent through the 1-meter combustor module

The determinants and employment effects of international outsourcing: the case of Italy

Using a new firm-level database, we address micro determinants and employment consequences of international production outsourcing (INPOU). Regarding the former, we confirm that INPOU in Italy mostly counters emerging economies. threats to traditional manufactured goods: INPOU disproportionately targets developing countries and intensifies in sectors with stiffest Chinese competition. Concerning employment consequences, we concur with previous literature that INPOU firms. domestic employment performances are no worse than at matching no-INPOU firms. However, given Italy.s industrial structure (small-sized networked enterprises), INPOU might negatively affect subcontracting firms. Our evidence that employment performances worsen in the productive segments with strongest INPOU supports our conjecture.international outsourcing, multinational firms

The Effect of Rating Agencies on Herd Behaviour

This paper purports to provide some evidence on the effect of rating agencies on herding in financial markets. By means of a laboratory experiment, we investigate the effect and interaction between private and public information. Previous experiments showed that lemmings behaviour can survive in a market context where information is private (Hey and Morone, 2004), and that an experimental market can be very volatile and not efficient in transmitting information (Alfarano et al., 2006). We study experimentally, if socially undesirable behaviour - that survives in a market contest - may be eliminated owing to the presence of rating agencies.herd behaviour; informational cascades; rating agency; bubble

Estimating Multidimensional Persistent Homology through a Finite Sampling

An exact computation of the persistent Betti numbers of a submanifold $X$ of a Euclidean space is possible only in a theoretical setting. In practical situations, only a finite sample of $X$ is available. We show that, under suitable density conditions, it is possible to estimate the multidimensional persistent Betti numbers of $X$ from the ones of a union of balls centered on the sample points; this even yields the exact value in restricted areas of the domain. Using these inequalities we improve a previous lower bound for the natural pseudodistance to assess dissimilarity between the shapes of two objects from a sampling of them. Similar inequalities are proved for the multidimensional persistent Betti numbers of the ball union and the one of a combinatorial description of it