Experimental investigation on the use of waste elastomeric polymers for bitumen modification

The study described in this paper focused on the possible use of waste products coming from the production of styrene-butadiene rubber (SBR) and polybutadiene rubber (PBR), as bitumen modifiers. Modified binders containing these products were prepared in the laboratory with different polymer dosages and were thereafter subjected to the evaluation of empirical and rheological properties. For comparative purposes, the study also considered SBR and PBR products of premium quality. Ageing effects were also taken into account by means of proper laboratory simulations. Obtained results indicated that the two types of polymer (SBR and PBR) have completely different effects on the rheology and expected performance of the resulting modified binders. In particular, while the two polymers showed similar effects in terms of resistance to permanent deformation, the SBR products proved to be superior from the viewpoint of fatigue resistance. However, only minor differences were found when comparing the effects produced by premium quality and waste polymers. As a result of the experimental findings, it was concluded that the use of waste SBR polymers can be an attractive solution for the production of affordable modified binders

The Mw 6.3, 2009 L’Aquila earthquake: source, path and site effects from spectral analysis of strong motion data

The strong motion data of 2009 April 6 L’Aquila (Central Italy) earthquake (Mw = 6.3) and of 12 aftershocks (4.1 ≤ Mw ≤ 5.6) recorded by 56 stations of the Italian strong motion network are spectrally analysed to estimate the source parameters, the seismic attenuation, and the site amplification effects. The obtained source spectra for S wave have stress drop values ranging from 2.4 to 16.8 MPa, being the stress drop of the main shock equal to 9.2 MPa. The spectral curves describing the attenuation with distance show the presence of shoulders and bumps, mainly around 50 and 150 km, as consequence of significant reflected and refracted arrivals from crustal interfaces. The attenuation in the first 50 km is well described by a quality factor equal to Q( f ) = 59 f 0.56 obtained by fixing the geometrical spreading exponent to 1. Finally, the horizontal-to-vertical spectral ratio provides unreliable estimates of local site effects for those stations showing large amplifications over the vertical component of motion

Type 2 myocardial infarction: a diagnostic and therapeutic challenge in contemporary cardiology

In the expanding world of cardiovascular diseases, rapidly reaching pandemic proportions, the main focus is still on coronary atherosclerosis and its clinical consequences. However, at least in the Western world, middle-aged male patients with acute myocardial infarction are no more the rule. Due to a higher life expectancy and major medical advances, physicians are to treat older and frailer individuals, usually with multiple comorbidities. In this context, myocardial ischaemia and infarction frequently result from an imbalance between myocardial oxygen supply and demand\u2014i.e., type 2 myocardial infarction (T2MI), according to the current universal definition\u2014rather than coronary atherothrombosis. Moreover, the increasing use of high-sensitivity cardiac troponin assays has led to a heightened detection of T2MI\u2014often causing relatively little myocardial injury\u2014, which seems to have doubled its numbers in recent years. Nevertheless, owing to its multifaceted pathophysiology and clinical presentation, T2MI is still underdiagnosed. Perhaps more importantly, T2MI is also victim of undertreatment, as drugs that constitute the cornerstone of therapy in most cardiovascular diseases are much more unlikely to be prescribed in T2MI than in coronary atherothrombosis. In this paper, we review the recent literature on the classification, pathophysiology, epidemiology, and management of T2MI, trying to summarise the state-of-the-art knowledge about this increasingly important pathologic condition. Finally, based on the current scientific evidence, we also propose an algorithm that may be easily utilised in clinical practice, in order to improve T2MI diagnosis and risk stratification

Solar energetic particle events related to disk-centre full-halo coronal mass ejections

We have investigated the occurrence and characteristics of solar energetic particle (SEP) events related to full halo coronal mass ejections (FHCMEs) from source locations close to the central meridian of the Sun. Halo CMEs detected by SOHO/LASCO between 1996 and end of 2014 originating from source locations between solar longitudes E10 and W10 were first identified. The CMEs were divided in three groups according to the latitude of the source region: 26 equatorial events in the latitude range [N10, S10], 16 northern events in the range (N10,N20], and 22 southern events in the range (S10, S20]. We then searched for associated solar proton events based on SOHO/ERNE observations. In altogether 25 cases (13 equatorial, 6 northern, and 6 southern events) an association was found. For these events, we found good correlations of the peak intensities of 2MeV, 20MeV, and 68MeV protons with both the CME speed and the X-ray flare magnitude, as determined by the soft X-ray peak flux or the event integrated flux. The correlation coefficients ranged from 0.47 to 0.83 for the CME speed, from 0.63 to 0.88 for the X-ray peak flux and from 0.64 to 0.89 for the X-ray integrated flux depending on the proton energy.</div

Toward validation of simulated accelerograms via prediction equations for nonlinear SDOF response

Seismic structural risk analysis of critical facilities may require nonlinear dynamic analysis for which record selection is one of the key issues. Notwithstanding the increasing availability of database of strong-motion records, it may be hard to find accelerograms that fit a specific scenario (e.g., in terms of magnitude and distance) resulting from hazard assessment at the site of interest. A possible, alternative, approach can be the use of artificial and/or simulated ground motion in lieu of real records. Their employment requires systematic engineering validation in terms of structural response and/or seismic risk. Prediction equations for peak and cyclic inelastic single degree of freedom systems’ response, based on Italian accelerometric data, are discussed in this study as a possible benchmark, alongside real record counterparts, for the validation of synthetic records. Even if multiple events would be in principle required, an extremely preliminary validation is carried out considering only four simulated records of the 1980 Irpinia (southern Italy) M w 6.9 earthquake. Simulated records are obtained through a broadband hybrid integral-composite technique. Results show how this simulation method may lead to generally acceptable results. It is also emphasized how this kind of validation may provide additional results with respect to classical signal-to-signal comparison of real and simulated records

A Three-Dimensional Coupled Internal/External Simulation of a Film-Cooled Turbine Vane

A three-dimensional Navier-Stokes simulation has been performed for a realistic film-cooled turbine vane using the LeRC-HT code. The simulation includes the flow regions inside the coolant plena and film cooling holes in addition to the external flow. The vane is the subject of an upcoming NASA Glenn Research Center experiment and has both circular cross-section and shaped film cooling holes. This complex geometry is modeled using a multi-block grid which accurately discretizes the actual vane geometry including shaped holes. The simulation matches operating conditions for the planned experiment and assumes periodicity in the spanwise direction on the scale of one pitch of the film cooling hole pattern. Two computations were performed for different isothermal wall temperatures, allowing independent determination of heat transfer coefficients and film effectiveness values. The results indicate separate localized regions of high heat transfer coefficient values, while the shaped holes provide a reduction in heat flux through both parameters. Hole exit data indicate rather simple skewed profiles for the round holes, but complex profiles for the shaped holes with mass fluxes skewed strongly toward their leading edges

Comparison between empirical predictive equations calibrated at global and national scale and the Italian strong-motion data

In Italy in the last years many ground motion prediction equations (hereinafter GMPEs) were calibrated both at national and regional scale using weak and strong motion data recorded in the last 30 years by several networks. Moreover many of the Italian strongest earthquakes were included in global datasets in order to calibrate GMPEs suitable to predict ground-motion at very large scale. In the last decade the Sabetta and Pugliese (1996) relationships represented a reference for the ground motion predictions in Italy. At present all Italian strong-motion data, recorded from 1972 by RAN (Italian Accelerometric Network), and more recently by other regional networks (e.g. RAIS, Strong motion network of Northern Italy), are collected in ITACA (ITalian ACcelerometric Archive). Considering Italian strong-motion data with Mw  4.0 and distance (Joyner-Boore or epicentral) up to 100 km, new GMPEs were developed by Bindi et al. (2009), aimed at replacing the older Italian relationships. The occurrence of the recent 23rd December 2008, Mw 5.4, Parma (Northern Italy) earthquake and the 6th April 2009, Mw 6.3, L’Aquila earthquake, allowed to upgrade the ITACA data set and gave us the possibility to validate the predictive capability of many GMPEs, developed using Italian, European and global data sets. The results are presented in terms of quality of performance (fit between recorded and predicted values) using the maximum likelihood approach as explained in Spudich et al. (1999). Considering the strong-motion data recorded during the L’Aquila sequence the considered GMPEs, in average, overestimate the observed data, showing a dependence of the residuals with distance in particular at higher frequencies. An improvement of fit is obtained comparing all Italian strong-motion data included in ITACA with the European GMPEs calibrated by Akkar and Bommer (2007 a,b) and the global models calibrated by Cauzzi and Faccioli (2008). In contrast, Italian data seem to attenuate faster than the NGA models calibrated by Boore and Atkinson (2008), in particular at higher frequencies

Laser Detection and Imaging Techniques for Surface Examination

A coherent laser probe provides the basis for the recording of complex SAW distributions. Using three or more scans, the surface wave velocity can be deducep with an accuracy of a few parts in 105. Such measurements are sufficiently sensitive to detect small changes in surface characteristics; as an example, results will be presented on the effect of doping a Si surface. It is also possible to improve the accuracy of the basic elastic constants of the material by reference to the velocity characteristic. Of particular importance is the fact that this technique provides evidence on the effective value of these constants close to a surface; it is, therefore potentially useful for surface layer characterisation. Surface defects can be detected by means of scattered waves in both the forward as the reverse directions. In principle, either can be used to image the defect. Using both these components, the defect size and location can be determined with improved accuracy

Ground Motion Prediction Equations Derived from the Italian Strong Motion Database

We present a set of ground motion prediction equations (GMPEs) derived for the geometrical mean of the horizontal components and the vertical, considering the latest release of the strong motion database for Italy. The regressions are performed over the magnitude range 4–6.9 and considering distances up to 200 km. The equations are derived for peak ground acceleration (PGA), peak ground velocity (PGV) and 5%-damped spectral acceleration at periods between 0.04 and 2 s. The total standard deviation (sigma) varies between 0.34 and 0.38 log10 unit, confirming the large variability of ground shaking parameters when regional data sets containing small to moderate magnitude events (M < 6) are used. The between-stations variability provides the largest values for periods shorter than 0.2 s while, for longer periods, the between-events and between-stations distributions of error provide similar contribution to the total variabilit

Organizational culture, leadership style and effectiveness: A case study of middle eastern construction clients

During the last few decades, organizational effectiveness has received a great deal of attention in many industrial sectors. As a result, a variety of models have been formulated which measure organizational performance. In the construction industry, two factors have subsequently captured the imagination and interest of researchers and practitioners alike: the culture of the organization and the leadership style of project managers. This focus places a requirement upon construction organizations to recognize and understand their organizational culture, and equally, to clearly communicate it to their employees as part of their capitalist drive of constantly improving performance, productivity and profit. Traditional ways of conducting construction business require a sound understanding of the technical and managerial demands of executing projects, which in turn, places an increased emphasis upon the management and leadership competencies of individual project managers. The purpose of the research is to explore the relationship between organizational culture, authentic leadership style and effectiveness within the context of a case study investigation centred on Middle Eastern construction clients and their project managers. The outcomes of the investigation, which include the presentation of an explanatory model, indicate that organizational culture is directly and positively related to performance and effectiveness, while project managers' leadership style has an indirect relationship to effectiveness. A strong organizational culture is therefore deemed critical to organizational performance