An update on the Tower of Pisa

The Leaning Tower of Pisa has been stabilised in the years 1999–2000 by an International Committee appointed by the Italian Government. An analysis of the whole history of the monument, starting from its construction in the XII century and including the results of the modern monitoring of XIX and XX century led the Committee to the conclusion that the Tower is affected by a phenomenon of instability of the equilibrium, depending on the deformability and not on the strength of the foundation soils. The stabilisation intervention, totally respectful of the integrity of the monument, consisted in slightly decreasing the inclination of the Tower by underexcavating a small volume of soil beneath the north side of the foundation. The paper briefly reports the analysis and the intervention; the observation of the behaviour in the twenty years elapsed since then allows some preliminary evaluation of the future behaviour

Leaning Tower of Pisa: Behaviour after Stabilization Operations

It is well known that the foundations of the Leaning Tower of Pisa were stabilised using the method of underexcavation to reduce the southward inclination of the Tower by about 10 percent in combination with controlling the seasonally fluctuating water table beneath the north side. Having been closed to the public since early in 1990, the Tower was re-opened in December 2001. The paper summarises the response of the Tower during the period of implementation of the stabilisation works. Monitoring of the movements of the Tower has been continuing and the observations obtained since 2001 are presented. It is shown that over the six years between 2003 and 2008 the induced rate of northward rotation of the Tower has been steadily reducing to less than 0.2 arc seconds per year. Similarly the rate of induced settlement of the centre of the foundation has been steadily reducing and is approaching the background rate of settlement of the Piazza. Piezometer measurements close to the north side of the foundation shows that the drainage system has been successful in stabilising the groundwater levels beneath the north side of the Tower’s foundation. The paper concludes with a brief discussion on the possible future behaviour of the Tower

Numerical simulation of the heat penetration in two-plate arc welding

A mathematical model and numerical simulation of the three-dimensional and transient metal arc-welding process is presented. The heat source is considered as spatially distributed following a centered Gaussian bell, while the substract material (Al 6063) is assumed homogeneous and isotropic with temperature-dependent thermal properties. Radiation and convection are also calculated through an empirical temperature dependent correlation. Phase-change phenomenon is included as a discontinuity in the material specific heat. Calculations were performed by using a finite volume code (CFX4.2TM). Computed heat penetration and weld metal area are found to be in good agreement with experimental data

Numerical simulation of the heat penetration in two-plate arc welding

A mathematical model and numerical simulation of the three-dimensional and transient metal arc-welding process is presented. The heat source is considered as spatially distributed following a centered Gaussian bell, while the substract material (Al 6063) is assumed homogeneous and isotropic with temperature-dependent thermal properties. Radiation and convection are also calculated through an empirical temperature dependent correlation. Phase-change phenomenon is included as a discontinuity in the material specific heat. Calculations were performed by using a finite volume code (CFX4.2TM). Computed heat penetration and weld metal area are found to be in good agreement with experimental data

Improved Method for the Seismic Design of Anchored Steel Sheet Pile Walls

This paper describes a new pseudostatic approach for an efficient seismic design of anchored steel sheet pile (ASSP) walls supported by shallow passive anchorages. As for other retaining structures, energy dissipation during strong earthquakes leading to reduced inertia forces can be achieved by allowing the activation of ductile plastic mechanisms. To this end, a robust method is required to identify all the possible yielding mechanisms and to guarantee the desired strength hierarchy. It is shown that dissipative mechanisms for ASSP walls correspond either to the local attainment of the soil shear strength in the supporting soil and around the anchor, or in the activation of a log-spiral global failure surface. A new limit equilibrium method is proposed to compute the critical acceleration of the system, corresponding to the actual mobilization of its strength, and the maximum internal forces in the structural members. Theoretical findings are validated against both existing dynamic centrifuge data and the results of original pseudostatic and fully dynamic numerical analyses

Strategies for analyzing highly enriched IP-chip datasets

BACKGROUND: Chromatin immunoprecipitation on tiling arrays (ChIP-chip) has been employed to examine features such as protein binding and histone modifications on a genome-wide scale in a variety of cell types. Array data from the latter studies typically have a high proportion of enriched probes whose signals vary considerably (due to heterogeneity in the cell population), and this makes their normalization and downstream analysis difficult. RESULTS: Here we present strategies for analyzing such experiments, focusing our discussion on the analysis of Bromodeoxyruridine (BrdU) immunoprecipitation on tiling array (BrdU-IP-chip) datasets. BrdU-IP-chip experiments map large, recently replicated genomic regions and have similar characteristics to histone modification/location data. To prepare such data for downstream analysis we employ a dynamic programming algorithm that identifies a set of putative unenriched probes, which we use for both within-array and between-array normalization. We also introduce a second dynamic programming algorithm that incorporates a priori knowledge to identify and quantify positive signals in these datasets. CONCLUSION: Highly enriched IP-chip datasets are often difficult to analyze with traditional array normalization and analysis strategies. Here we present and test a set of analytical tools for their normalization and quantification that allows for accurate identification and analysis of enriched regions

Interactive management control via analytic hierarchy process (AHP). An empirical study in a public university hospital.

Management control in public university hospitals is a challenging task because of continuous changes due to external pressures (e.g. economic pressures, stakeholder focuses and scientific progress) and internal complexities (top management turnover, shared leadership, technological evolution, and researcher oriented mission). Interactive budgeting contributed to improving vertical and horizontal communication between hospital and stakeholders and between different organizational levels. This paper describes an application of Analytic Hierarchy Process (AHP) to enhance interactive budgeting in one of the biggest public university hospital in Italy. AHP improved budget allocation facilitating elicitation and formalization of units’ needs. Furthermore, AHP facilitated vertical communication among manager and stakeholders, as it allowed multilevel hierarchical representation of hospital needs, and horizontal communication among staff of the same hospital, as it allowed units’ need prioritization and standardization, with a scientific multi-criteria approach, without using complex mathematics. Finally, AHP allowed traceability of a complex decision making processes (as budget allocation), this aspect being of paramount importance in public sectors, where managers are called to respond to many different stakeholders about their choices

Description of Synergus castaneus n. sp. (Hymenoptera: Cynipidae: Synergini) Associated with an Unknown Gall on Castanea spp. (Fagaceae) in China

Abstract A species of the tribe Synergini (Hymenoptera: Cynipidae) was reared from a gall collected in China on Castanea mollissima Blume and Castanea seguinii Dode. The morphological features of this gall wasp indicate that it is an undescribed species belonging to the genus Synergus and is herein described as a new species, Synergus castaneus Pujade-Villar, Bernardo et Viggiani sp. nov. (Hymenoptera Cynipidae: Synergini). This is the first known instance of a species of Synergus emerging from Castanea galls (Fagaceae). Data on the diagnosis, distribution, and biology of the new species are given. Morphological features of this species are discussed and illustrated. No other known gall-inducing species emerged from the collected galls, whereas tens of specimens of parasitoids and adults of the inquiline micromoth Andrioplecta pulverula Meyrick (Lepidoptera: Tortricidae) did. 28S-D2 and COI sequences confirmed that S. castaneus is a distinct species belonging to the genus Synergus

role of winter host plants in vineyard colonization and phenology of zygina rhamni hemiptera cicadellidae typhlocybinae

Abstract Zygina rhamni Ferrari (Hemiptera: Cicadellidae: Typhlocybinae) is a mesophyll-feeding leafhopper that infests grapevine, Vitis vinifera L. This leafhopper's overwintering strategy and the dynamics of its vineyard colonization, relative to the distance between the grapevines and the winter host plants and different grapevine vegetative densities, are described herein. This species shows a facultative heteroecious life cycle. In autumn, it migrates from vineyards to bramble, Rubus gr. fruticosus, and rose, Rosa chinensis Jacquin. On these host plants, females lay eggs that start to hatch at the end of March. Adults that developed on bramble colonize grapevines beginning in May; the leaf fall of rose, which takes place during the first half of April, probably causes the death of unhatched eggs and nymphs. We found that overwintering females can move back to vineyards and lay eggs until early June. The dynamics of vineyard colonization by the leafhopper involved initial concentration in areas close t..

ALERT Doctoral School 2012: advanced experimental techniques in geomechanics

The twenty-second session of the European Graduate School 2012 (called usually ALERT Doctoral School) entitled Advanced experimental techniques in geomechanics is organized by Cino Viggiani, Steve Hall and Enrique Romero.Postprint (published version