Multi-pollutants impact on modern cement built heritage

It is well known that the deposition of gaseous pollutants and aerosols plays a major role in causing the deterioration of monuments and built cultural heritage in European cities. Despite of many studies dedicated to the environmental damage of cultural heritage, in case of cement mortars, commonly used in the 20th century architecture, the deterioration due to air multipollutants impact, especially the formation of black crusts, is still not well explored making this issue a challenging area of research. This work centers on cement mortars – environment interactions, focusing on the diagnosis of the damage on the modern built heritage due to air multi-pollutants. For this purpose three sites, exposed to different urban areas in Europe, were selected for sampling and subsequent laboratory analyses: Centennial Hall, Wroclaw (Poland), Chiesa dell'Autostrada del Sole, Florence (Italy), Casa Galleria Vichi, Florence (Italy). The sampling sessions were performed taking into account the height from the ground level and protection from rain run off (sheltered, partly sheltered and exposed areas). The complete characterization of collected damage layer and underlying materials was performed using a range of analytical techniques: optical and scanning electron microscopy, X ray diffractometry, differential and gravimetric thermal analysis, ion chromatography, flash combustion/gas chromatographic analysis, inductively coupled plasma-optical emission spectrometer. The data were elaborated using statistical methods (i.e. principal components analyses) and enrichment factor for cement mortars was calculated for the first time. The results obtained from the experimental activity performed on the damage layers indicate that gypsum, due to the deposition of atmospheric sulphur compounds, is the main damage product at surfaces sheltered from rain run-off at Centennial Hall and Casa Galleria Vichi. By contrast, gypsum has not been identified in the samples collected at Chiesa dell'Autostrada del Sole. This is connected to the restoration works, particularly surface cleaning, regularly performed for the maintenance of the building. Moreover, the results obtained demonstrated the correlation between the location of the building and the composition of the damage layer: Centennial Hall is mainly undergoing to the impact of pollutants emitted from the close coal power stations, whilst Casa Galleria Vichi is principally affected by pollutants from vehicular exhaust in front of the building.

Nonlinear Control Strategies for Cooperative Control of Multi-Robot Systems

This thesis deals with distributed control strategies for cooperative control of multi-robot systems. Specifically, distributed coordination strategies are presented for groups of mobile robots. The formation control problem is initially solved exploiting artificial potential fields. The purpose of the presented formation control algorithm is to drive a group of mobile robots to create a completely arbitrarily shaped formation. Robots are initially controlled to create a regular polygon formation. A bijective coordinate transformation is then exploited to extend the scope of this strategy, to obtain arbitrarily shaped formations. For this purpose, artificial potential fields are specifically designed, and robots are driven to follow their negative gradient. Artificial potential fields are then subsequently exploited to solve the coordinated path tracking problem, thus making the robots autonomously spread along predefined paths, and move along them in a coordinated way. Formation control problem is then solved exploiting a consensus based approach. Specifically, weighted graphs are used both to define the desired formation, and to implement collision avoidance. As expected for consensus based algorithms, this control strategy is experimentally shown to be robust to the presence of communication delays. The global connectivity maintenance issue is then considered. Specifically, an estimation procedure is introduced to allow each agent to compute its own estimate of the algebraic connectivity of the communication graph, in a distributed manner. This estimate is then exploited to develop a gradient based control strategy that ensures that the communication graph remains connected, as the system evolves. The proposed control strategy is developed initially for single-integrator kinematic agents, and is then extended to Lagrangian dynamical systems.

Sense of Community in contexts of multi culture

The theme “Belongingness” has a central role in the current debate on Community Psychology and in daily life. To try to understand the consequences of these changes, the research focuses on the concept of Sense of Community. In fact, Sense of Community has always been a central tool (Sarason, 1974; MacMillan & Chavis, 1986) to study communities (McMillan, 2011; Nowell & Boyd, 2011) and for a long time has represented positive values and something to aspire to. However, current debates indicate that Sense of Community is an outmoded concept and underline the problematic issue of “promotion of Sense of Community” in contexts of multi culture. The aim of the present research is to analyze Sense of Community in context of multi culture, as we consider that it can still be a fundamental tool to study and understand communities. In particular we are interested in understanding the role of Multiple Sense of Community (Brodsky, 2009) on Identity and Wellbeing (and its dimensions). We focused on a specific context, the Station Zone in Reggio Emilia, that is characterized by high levels of cultural diversity and different social problems (Giovannini & Vezzali, 2011). The research is developed and divided into two parts. The first part consists of an exploratory qualitative study that analyzes meanings of community among leaders of different ethnic groups living in the Station Zone. The second part consists of a “General Model” study and four parallel studies to analyze Multiple Sense of Community in different ethnic groups (Albanians, Moroccans, Chinese and Italians. The results indicate the different role of Multiple SOC in the relation between Identity and Wellbeing, in particular the relevance of Relational SOC and its different implications. Moreover, the factor “culture” represents an significant element in order to consider differences among ethnic groups.