Modeling cascading failures in "systems of systems" with uncertain behavior

International audienceWe model cascading failures in interdependent critical infrastructures (CIs). We adopt a model-ing framework based on simulation, which accounts for the physical specialization of the components and their interdependencies. We analyze cascading failures triggered by the intentional removal of a single com-ponent in the CIs and study the influence of the systems operating safety margins and interdependency para-meters on the consequences of the cascade. Uncertainties in the model parameters are propagated, within a probabilistic representation framework

Young Children’s cliques : a study on processes of peer acceptance and cliques aggregation

A considerable amount of research has examined the link between children’s peer acceptance, which refers to the degree of likability within the peer group, social functioning and emotional wellbeing, at a same age and in a long term perspective, pointing out to the contribution of peer acceptance for mental wellbeing. Our study proposes a sociometric methodology that, differently from many studies focused on individual classifications of social status, moves to the analysis of affiliative social networks within the class group. This study describes how individual factors such as socio-emotional competence, temperament, and linguistic skills are related to positive reciprocated nominations (=RNs) and examines the cliques generated by reciprocal nominations according to similarities (socio-emotional competence, temperament and linguistic skills) among cliques’ members. Eighty-four preschool children (M age = 62.5 months) were recruited. The Sociometric Interview to assess RNs and the Peabody Picture Vocabulary Test - Revised (PPVT-R; Dunn & Dunn, 1981) to assess receptive language were administered; the Social Competence and Behaviour Evaluation Short Form questionnaire (SCBE-30; LaFreniere & Dumas, 1996) and the Quit Temperament Scale (Axia, 2002) were filled in by the teachers. Results showed that children with higher RNs presented higher scores in social orientation, positive emotionality, motor activity, linguistic skills and social competence (trend), and exhibited lower anxietywithdrawal. The analysis of cliques revealed that children preferred playmates with similar features: social competence, anger-aggression (trend), social orientation, positive emotionality, inhibition to novelty, attention, motor activity (trend) and linguistic skills. These findings provide insights about processes of peer affiliation, highlighting the role of socio-emotional functioning and linguistic skills.peer-reviewe

A stochastic framework for uncertainty analysis in electric power transmission systems with wind generation

International audienceThe purpose of this work is the analysis of the uncertainties affecting an electric transmission network with wind power generation and their impact on its reliability. A stochastic model was developed to simulate the operations and the line disconnection and reconnection events of the electric network due to overloads beyond the rated capacity. We represent and propagate the uncertainties related to consumption variability, ambient temperature variability, wind speed variability and wind power generation variability. The model is applied to a case study of literature. Conclusions are drawn on the impact that different sources of variability have on the reliability of the network and on the seamless electric power supply. Finally, the analysis enables identifying possible system states, in terms of power request and supply, that are critical for network vulnerability and may induce a cascade of line disconnections leading to massive network blackout

Optimizing protections against cascades in network systems: A modified binary differential evolution algorithm

International audienceThis paper addresses the optimization of protection strategies in critical infrastructures within a complex network systems perspective. The focus is on cascading failures triggered by the intentional removal of a single network component. Three different protection strategies are proposed that minimize the consequences of cascading failures on the entire system, on predetermined areas or on both scales of protective intervention in a multi-objective optimization framework. We optimize the three protection strategies by devising a modified binary differential evolution scheme that overcomes the combinatorial complexity of this optimization problem. We exemplify our methodology with reference to the topology of an electricity infrastructure, i.e. the 380 kV Italian power transmission network. We only focus on the structure of this network as a test case for the suggested protection strategies, with no further reference on its physical and electrical properties

Risk assessment of a bulk cryogenic tank: Beyond the Leak-Before-Break criterion

International audienceThe increase in the size and production capacity of air separation plants has boosted the need of developing methodologies to properly assess the risk related to major releases of liquefied gas. In this respect, the Leak-Before-Break (LBB) assessment is currently adopted to demonstrate the safety of the structures containing liquefied gas, under the assumption that the tank is always operated in nominal conditions. This assumption is questioned in this paper, which proposes a new methodology for the assessment of the risks related to cryogenic tank catastrophic rupture. The methodology provides a comprehensive understanding of the issues associated to the worst case rupture scenario: from the investigation of the causes of the undesirable operating conditions up to the analysis of the associated structural consequences, within a probabilistic framewo

Analysis of the safety efficiency of a road network: a real case study

In this paper, recently introduced topological measures of interconnection and efficiency of network systems are applied to the safety analysis of the road transport system of the Province of Piacenza in Italy. The vulnerability of the network is evaluated with respect to the loss of a road link, e.g. due to a car accident, road work or other jamming occurrences. Eventually, the improvement in the global and local safety indicators following the implementation of a road development plan is evaluated

A Multi-Objective Memetic Optimization Method for Power Network Cascading Failures Protection

International audienceReliable and safe power grid operation requires the anticipation of cascading failures and the establishment of appropriate protection plans for their management. In this paper, we address this latter problem by line switching and propose a multi-objective memetic algorithm (MOMA), which combines the binary differential evolution algorithm with the non-dominated sorting mechanism and the Lamarckian local search. The 380 kV Italian power transmission network is used as a realistic test case

Progetto Life+ 08NAT/IT/000369“GYPSUM”. Primi risultati sulle analisi chimiche delle acque nei gessi dell’Emilia Romagna

Dal 2010 è in corso il Progetto Life+ 08NAT/IT/000369 “Gypsum” finalizzato alla tutela e gestione dei principali ambienti gessosi dell’Emilia-Romagna e cofinanziato dall’Unione Europea. Nell’ambito dell’Azione A3 è previsto un monitoraggio pluriennale dei principali acquiferi carsici sotto l’aspetto chimico e microbiologico. In questo lavoro vengono presentati i primi risultati di questo monitoraggio idrochimico.Since 2010 a Project Life + 08NAT/IT/000369 “Gypsum” is running, dealing with the safeguard and management of the main gypsum environments of Emilia Romagna region and cofinanced by the European Union. Action A3 of this Project is concerned with the pluriannual hydrochemical and microbiological monitoring of the most important gypsum aquifers. In this paper the first results of this hydrochemical monitoring are presented

Identification of functional apple scab resistance gene promoters

Apple scab (Venturia inaequalis) is one of the most damaging diseases affecting commercial apple production. Some wild Malus species possess resistance against apple scab. One gene, HcrVf2, from a cluster of three genes derived from the wild apple Malus floribunda clone 821, has recently been shown to confer resistance to apple scab when transferred into a scab-susceptible apple variety. For this proof-of-function experiment, the use of the 35S promoter from Cauliflower mosaic virus was reliable and appropriate. However, in order to reduce the amount of non-plant DNA in genetically modified apple to a minimum, with the aim of increasing genetically modified organism acceptability, these genes would ideally be regulated by their own promoters. In this study, sequences from the promoter region of the three members of the HcrVf gene family were compared. Promoter constructs containing progressive 5′ deletions were prepared and used for functional analyses. Qualitative assessment confirmed promoter activity in apple. Quantitative promoter comparison was carried out in tobacco (Nicotiana glutinosa) and led to the identification of several promoter regions with different strengths from a basal level to half the strength of the 35S promoter from Cauliflower mosaic viru

Quantum information protocols in complex entangled networks

Quantum entangled networks represent essential tools for Quantum Communication, i.e. the exchange of Quantum Information between parties. This work consists in the theoretical study of continuous variables (CV) entangled networks - which can be deterministically generated via multimode squeezed light - with complex topology. In particular we investigate CV complex quantum networks properties for quantum communication protocols. We focused on the role played by the topology in the implementation and the optimization of given characteristics of our entangled resource that are useful for a specific quantum communication task, i.e. the creation of an entanglement link between two arbitrary nodes of the resource we are provided with. We implemented an analytical procedure for the generation of entangled complex networks, their optimization and their manipulation via global linear optics operations. We also developed a numerical procedure, based on an evolutionary algorithm, for manipulating entanglement connections via local linear optics operations. Finally, we analyzed the re-shaping of our entangled resource via homodyne measurements