A hybrid model for mapping simplified seismic response via a GIS-metamodel approach

In earthquake-prone areas, site seismic response due to lithostratigraphic sequence plays a key role in seismic hazard assessment. A hybrid model, consisting of GIS and metamodel (model of model) procedures, was introduced aimed at estimating the 1-D spatial seismic site response in accordance with spatial variability of sediment parameters. Inputs and outputs are provided and processed by means of an appropriate GIS model, named GIS Cubic Model (GCM). This consists of a block-layered parametric structure aimed at resolving a predicted metamodel by means of pixel to pixel vertical computing. The metamodel, opportunely calibrated, is able to emulate the classic shape of the spectral acceleration response in relation to the main physical parameters that characterize the spectrum itself. Therefore, via the GCM structure and the metamodel, the hybrid model provides maps of normalized acceleration response spectra. The hybrid model was applied and tested on the built-up area of the San Giorgio del Sannio village, located in a high-risk seismic zone of southern Italy. Efficiency tests showed a good correspondence between the spectral values resulting from the proposed approach and the 1-D physical computational models. Supported by lithology and geophysical data and corresponding accurate interpretation regarding modelling, the hybrid model can be an efficient tool in assessing urban planning seismic hazard/risk. © Author(s) 2014

Thermal, mechanical and electrical performance of structural epoxy resins filled with carbon nanofibers

Carbon nanofibers (CNFs) were heat-treated at 1100 & DEG;C (CNF1100) and 2500 & DEG;C (CNF2500), respectively, and embedded as fillers at different mass percentages into an epoxy mixture. The paper aims at evaluating, through a comparison between the two different types of resulting nanocomposites, the influence of the CNF heat treatment on the thermal, mechanical, and electrical performance of the formulated samples. Thermogravimetric analysis (TGA) showed oxidative stability in the air of CNF2500 approximately 200 & DEG;C higher than the CNF1100 ones. The first oxidation stage of the resins embedding the two typologies of CNFs falls between 380 and 480 & DEG;C. This means that the temperature of the heat treatment of the nanofiller does not influence the temperature at which the thermodegradation of the nanocomposites starts. Differential Scanning Calorimetry (DSC) data show that the highest degree of cure (DC) was recorded for the epoxy samples filled with CNF2500. CNF thermal treatment increases the direct current (dc) conductivity of the nanocomposite by 3 orders of magnitude around the electrical percolation threshold (EPT) and increases the storage modulus of the CNF2500-based resins up to 60 & DEG;C compared with the unfilled resin. The peculiar wall structure of CNF1100 determines a further slight enhancement. Tunneling Atomic Force Microscopy (TUNA) reveals that the CNFs are evenly distributed on the nanodomains showing higher electric current values for samples loaded with CNF2500

A qualitative examination of police officers\u27 questioning of children about repeated events

For an offender to be convicted in relation to repeated child abuse, most jurisdictions require that each separate act be identified with reasonable precision with reference to time, place, or some other unique contextual detail (S v. R, 1989). The current study provided a qualitative examination of the way in which police officers assist children to identify and distinguish between occurrences of a repeated event. Field, as well as mock interviews (about an innocuous staged event) were examined, with child witnesses\u27 ages ranging from 3 to 16 years. Overall, several problems in the questioning were highlighted. These included: over-reliance on specific questions, use of \u27labels\u27 for occurrences without inquiring as to whether these were unique, and frequent shifting of the focus between occurrences. The implications of these findings are discussed. <br /

How do population movements fit within the framework of systemic risk?

Population movements are key elements shaping today's complex and interconnected societies. Movement of people underpins the circulation of capital, knowledge, ideas, culture, values and resources with systemic benefits but it also produces diverse risk implications. The varied and complex implications of human mobility (and immobility) are still poorly understood by existing systemic risk approaches. This literature review approaches human mobility from a more comprehensive and complex standpoint to understand how it fits within a wider framework of systemic risk. In this article, we explore the complementary ways in which movements matter for systemic risk considerations, namely as: 1) a dynamic force that shapes exposure, vulnerability and resilience to disasters across places and scales; 2) a feature and consequence of disasters that has the potential to amplify, extend and prolong the impacts of hazards, and 3) a lifeline for people and societies worldwide, whose disruption has significant implications on systemic risk globally. These considerations have important theoretical consequences for the integration of population movements in systemic risk frameworks, and they propose practical lessons learned for the disaster risk reduction arena. We conclude that human mobility should not be understood as a negative impact that must be prevented and mitigated but as a positive phenomenon which enablement and protection a will lead to positive resilience outcomes and the reduction of risks

Workplace stressors for investigative interviewers of child-abuse victims

Purpose - This study aimed to identify the nature and prevalence of workplace stressors faced by interviewers of child sexual assault victims.Design/methodology/approach - Sixty-eight professionals (police and child protection workers) were invited to anonymously post their perceptions of workplace stressors on an internet forum as part of an investigative interviewing online training course. Specifically, participants were asked to reflect on salient sources of stress encountered in their role of interviewing sexually abused children.Findings - Three key stressors were identified across the study&rsquo;s professional groups: (1) inadequate recognition of specialised skills; (2) high workload demands; and (3) interagency tensions. Consistent with previous research, exposure to child abuse reports was not raised as a stressor.Research limitations/implications - Our study generated suggestions for modifying management practices; however, future research should identify and trial strategies for improving workplace climate in child abuse investigation.Practical implications - As the stressors isolated by participants related to workplace climate rather than exposure to victims&rsquo; accounts of child abuse, minimising negative consequences of work stressors requires changes to workplace culture and practice. Workplace climates need to be modified so that the demands are offset by resources. Originality/value - Because of its online, anonymous nature, this was the first study to offer participants the opportunity to honestly disclose primary sources of stress in child abuse investigation. The research also makes a much-needed contribution to an area of police practice that is vital yet often overlooked

Optimization of graphene-based materials outperforming host epoxy matrices

The degree of graphite exfoliation and edge-carboxylated layers can be controlled and balanced to design lightweight materials characterized by both low electrical percolation thresholds (EPT) and improved mechanical properties. So far, this challenging task has been undoubtedly very hard to achieve. The results presented in this paper highlight the effect of exfoliation degree and the role of edge-carboxylated graphite layers to give self-assembled structures embedded in the polymeric matrix. Graphene layers inside the matrix may serve as building blocks of complex systems that could outperform the host matrix. Improvements in electrical percolation and mechanical performance have been obtained by a synergic effect due to finely balancing the degree of exfoliation and the chemistry of graphene edges which favors the interfacial interaction between polymer and carbon layers. In particular, for epoxy-based resins including two partially exfoliated graphite samples, differing essentially in the content of carboxylated groups, the percolation threshold reduces from 3 wt% down to 0.3 wt%, as the carboxylated group content increases up to 10 wt%. Edge-carboxylated nanosheets also increase the nanofiller/epoxy matrix interaction, determining a relevant reinforcement in the elastic modulus

Multiscale Composites: Assessment of a Feasible Manufacturing Process

A very interesting field of research on advanced composite materials is the possibility to integrate new functionalities and specific improvements acting on the matrix of the composite by means of a nanocharged resin. In this way, the composite becomes a so-called "multiscale composite" in which the different phases change from nano to macro scale. For example, the incorporation of nanoscale conductive fillers with intrinsically high electrical conductivity could allow a tailoring of this property for the final material. The properties of carbon nanotubes (CNT) make them an effective candidate as fillers in polymer composite systems to obtain ultralight structural materials with advanced electrical and thermal characteristics. Nevertheless, several problems are related to the distribution in the matrix and to the processability of the systems filled with CNT. Existing liquid molding processes such as resin transfer molding (RTM) and vacuum-assisted resin transfer molding (VARTM) can be adapted to produce carbon fiber reinforced polymer (CFRP) impregnated with CNT nanofilled resins. Unfortunately, the loading of more than 0.3-0.5% of CNT can lead to high resin viscosities that are unacceptable for such kind of processes. In addition to the viscosity issues that are related to the high CNT content, a filtration effect of the nanofillers caused by the fibrous medium may also lead to inadequate final component quality. This work describes the development of an effective manufacturing process of a fiber-reinforced multiscale composite panel, with a tetra-functional epoxy matrix loaded with carbon nanotubes to increase its electrical properties and with GPOSS to increase its resistance to fire. A first approach has been attempted with a traditional liquid infusion process. As already anticipated, this technique has shown considerable difficulties related both to the low level of impregnation achieved, due to the high viscosity of the resin, and to the filtration effects of the dispersed nanocharges. To overcome these problems, an opportunely modified process based on a sort of film infusion has been proposed. This modification has given an acceptable result in terms of impregnation and morphological arrangement of CNTs in nanofilled CFRP. Finally, the developed infiltration technique has been tested for the manufacture of a carbon fiber-reinforced panel with a more complex shape

Multi-technique characterization and thermal degradation study of epoxy modified resins designed for multifunctional applications

Tetraglycidyl methylene dianiline (TGMDA) was mixed with 1,4-Butanediol diglycidyl ether (BDE) (in a 4:1 mass ratio) and with a stoichiometric amount of the curing agent diaminodiphenyl sulfone which was solubilized at 120&nbsp;°C for 20&nbsp;min in the liquid mixture TGMDA + BDE. The so obtained unfilled epoxy resin matrix, denoted as ER, was blended with glycidyl polyhedral oligomeric silsesquioxane and carbon nanotubes in suitable proportions to obtain binary and ternary mixtures. Characterization of the formulated materials was performed using different experimental techniques, such as Dynamic mechanical analysis, Thermogravimetry (TG), Field emission scanning electron microscopy. Furthermore, the investigation of the flame behavior was carried out by the limiting oxygen index and mass loss calorimeter measurements. Direct current measurements and investigation by Tunneling atomic force microscopy of the conductive nanodomain map allowed the evaluation of the electrical properties of the developed nanofilled systems. The TG data related to thermal decomposition of ER and its binary and ternary mixtures were processed according to isoconversional kinetic analysis by assuming a non-Arrhenian behavior of the temperature function, and lifetime prediction was estimated at suitable relatively low temperatures and possible relation between the thermal stability and the presence of each component was discussed. This method of kinetic analysis paves the way for the possibility of evaluating in a more realistic way, on the basis of thermal stability, the potential application of structural resins with primary load functions in contact with hot areas of aeronautical aircraft engines

Kinematic Segmentation and Velocity in Earth Flows: A Consequence of Complex Basal-slip Surfaces

Abstract We investigated relations between geomorphic structures, movement velocity, and basal-slip surface geometry within individual kinematic domains of two large earth flows in the Apennine Mountains of southern Italy: the "Montaguto" earth flow and the "Mount Pizzuto" earth flow. Our analyses indicated that the earth flows are composed of distinct kinematic zones characterized by specific deformational patterns and longitudinal velocity profiles. Variations in velocity within individual kinematic zones is controlled by the geometry of the basal-slip surface, and, in particular by local variations in slope angle. Slip-surface geometry and slope also seem to control the density of extensional structures in driving earth-flow elements