The Dynamics of Semigroups of Contraction Similarities on the Plane

Indiana University-Purdue University Indianapolis (IUPUI)Given a parametrized family of Iterated Function System (IFS) we give sufficient conditions for a parameter on the boundary of the connectedness locus, M, to be accessible from the complement of M. Moreover, we provide a few examples of such parameters and describe how they are connected to Misiurewicz parameter in the Mandelbrot set, i.e. the connectedness locus of the quadratic family z^2+c

On the Fundamental Periods of Vibration of Flat-Bottom Ground-Supported Circular Silos containing Gran-like Material

Despite the significant amount of research effort devoted to understanding the structural behavior of grain-silos, each year a large number of silos still fails due to bad design, poor construction, with a frequency much larger than other civil structures. In particular, silos frequently fails during large earthquakes, as occurred during the 1999 Chi-Chi, Taiwan earthquake when almost all the silos located in Taichung Port, 70 km far from the epicenter, collapsed. The EQE report stated that "the seismic design of practice that is used for the design and construction of such facilities clearly requires a major revision". The fact indicates that actual design procedures have limits and therefore significant advancements in the knowledge of the structural behavior of silo structures are still necessary. The present work presents an analytical formulation for the assessment of the natural periods of grain silos. The predictions of the novel formulation are compared with experimental findings and numerical simulations

The "direct-five step procedure for existing buildings": development and first application

This paper provides design indications for the seismic retrofitting of existing frame buildings by means of fluid viscous dampers. They are based on a simplified procedure developed in the last years for new buildings and called "direct five-step procedure". This design procedure, which must be then followed by appropriate verification of the seismic behaviour through non-linear dynamic analyses, consists of 5 steps and is based on a prefixed seismic performance, such as a target damping ratio. The procedure aims at the full definition of the mechanical characteristics of the commercial non-linear viscous dampers, and at the estimation of the maximum forces both in the devices and in the structural elements (columns). In the case of new buildings, the objective of sizing the viscous dampers in such a way as to keep the structural elements within the linear elastic range even for "rare" earthquakes of high intensity is easily achievable. In the case of existing buildings designed for vertical loads only, the introduction of a damper system is not generally sufficient to keep the structural elements in the elastic range. Thus, it might be necessary to accept local plastic excursion of the structural elements, by taking into account the ductility capacity (albeit probably limited) of the existing building (hysteretic dissipations associated with damage in beams and columns). This paper reports the extension of the so-called "direct five-step procedure" to the case of existing buildings and its first application to a 6-storey frame structure case study, which is representative of reinforced concrete buildings designed for vertical loads only, before the enforcement of seismic codes

Research on the First Musique Concrète: The Case of Xenakis’s First Electroacoustic Pieces

Xenakis’s first electroacoustic pieces (Diamorphoses, 1957; Concret PH, 1958; Analogique B, 1959; Orient-Occident, 1960; and Bohor, 1962) can be called musique concrète. Indeed, these works use the concrète musique tape techniques. But their spirit and aesthetic is very different from those set forth in Pierre Schaeffer’s theories. In fact, these works are quite particular in their whole conception. The two authors of this article are researching this period of Xenakis’s electroacoustic music. In this article, they offer a brief survey of the issues these works raised. To illustrate some of these issues, they use Diamorphoses and Bohor as examples

Italian inner areas' strategic plans: a textual network analysis of the Appennino Emiliano and Madonie case studies

In 2012, the Italian government introduced the National Strategy for Inner Areas (SNAI accordingly with the Italian acronym). Local authorities and actors in inner areas were involved in the identification of the strengths and weaknesses of their territory and in the definition of development actions. This study proposes a textual network analysis of the strategic plans produced by two areas participating in the SNAI pilot project, one from the Centre-North of Italy (the Appennino Emiliano area) and one from the Southern part of the country (the Madonie area in Sicily). The analysis reveals that similarities between the two strategic plans emerge when the focus is on the territory and economic-related themes. At the same time, differences arise concerning the meaning and importance attributed to networking

Epidemiological patterns of asbestos exposure and spatial clusters of incident cases of malignant mesothelioma from the Italian national registry.

BACKGROUND: Previous ecological spatial studies of malignant mesothelioma cases, mostly based on mortality data, lack reliable data on individual exposure to asbestos, thus failing to assess the contribution of different occupational and environmental sources in the determination of risk excess in specific areas. This study aims to identify territorial clusters of malignant mesothelioma through a Bayesian spatial analysis and to characterize them by the integrated use of asbestos exposure information retrieved from the Italian national mesothelioma registry (ReNaM). METHODS: In the period 1993 to 2008, 15,322 incident cases of all-site malignant mesothelioma were recorded and 11,852 occupational, residential and familial histories were obtained by individual interviews. Observed cases were assigned to the municipality of residence at the time of diagnosis and compared to those expected based on the age-specific rates of the respective geographical area. A spatial cluster analysis was performed for each area applying a Bayesian hierarchical model. Information about modalities and economic sectors of asbestos exposure was analyzed for each cluster. RESULTS: Thirty-two clusters of malignant mesothelioma were identified and characterized using the exposure data. Asbestos cement manufacturing industries and shipbuilding and repair facilities represented the main sources of asbestos exposure, but a major contribution to asbestos exposure was also provided by sectors with no direct use of asbestos, such as non-asbestos textile industries, metal engineering and construction. A high proportion of cases with environmental exposure was found in clusters where asbestos cement plants were located or a natural source of asbestos (or asbestos-like) fibers was identifiable. Differences in type and sources of exposure can also explain the varying percentage of cases occurring in women among clusters. CONCLUSIONS: Our study demonstrates shared exposure patterns in territorial clusters of malignant mesothelioma due to single or multiple industrial sources, with major implications for public health policies, health surveillance, compensation procedures and site remediation programs

The effects of in-plane shear displacements at the springings of Gothic cross vaults

Extensive damages recorded during recent strong Italian earthquakes highlighted how vulnerable masonry vaults are and what deformations they receive from the rest of the building, which can be simulated as two phenomena: (i) a dynamic response of the vault itself, above the lateral walls and piers, and (ii) a pseudo-static response of the vault to imposed displacements at its springings, triggered by significant movement from the lateral walls and piers. This paper aims at improving knowledge in this field by simulating the second of these phenomena as static shear deformation at the springings. An experimental programme was set on a model of a typical quadripartite square Gothic cross vault (from the aisle of the Holyrood Abbey in Edinburgh). The test on a 1:4 scaled model had the shear displacement applied by moving two abutments in the longitudinal sense until failure, recording the crack pattern evolution and displacements of the ridges, identifying the diagonal cracks normal to the shear displacement that cause the damage and collapse in the vault. The crack pattern was validated with linear and non-linear numerical models, confirming particular observations like the uplift of the ridges and concentration of damage along the notional shear diagonal. Non-linear models are capable of capturing not only the crack pattern evolution, but also the vertical and horizontal displacements of the structure