Parametrical analysis of the railways dynamic response at high speed moving loads

The paper introduces some findings about a sensitivity analysis conducted on every geometrical and mechanical parameters which characterize the use of a railway superstructure at the high velocity. This analysis was carried out by implementing a forecast model that is derived from the simplified Gazetas and Dobry one. This model turns out to be particularly appropriate in the explication of problems connected to high velocity, since it evaluates both inertial and viscous effects activated by the moving load speed. The model implementation requires the transfer function determination that represents the action occurred by the bed surfaces on the railway and it therefore contains information concerning the geometrical and the mechanical characteristics of the embankment, of the ballast and of the sub-ballast. The transfer function H has been evaluated with the finite elements method and particularly, by resorting the ANSYS® code with a harmonic structural analysis in the frequencies field. The authors, from the critic examination of the system's dynamics response in its entirety, glean a series of observations both of a general and a specific character, finally attaining a propose of a design modification of the standard railway superstructure at the high velocity of train operation adopted today especially in Italy

The Use of Bloss Curve in The Exit Lanes of Road Intersections

The paper proposes the use of the Bloss curve (also known as biparametric or bi-hyperclothoid) as a braking curve in the exit lanes of road intersections. The main international standards continue using the clohoid as the principal transitional geometric element, even though the limits of its use in driving regimes with non-uniform speeds are known. The proposal to use the Bloss curve is aimed at overcoming these limitations and opening a debate on the possible need to codify, even in the international standards, the use of more suitable alternative braking curves. In this context, a kinematic study was conducted by comparing the main parameters of the motion (lateral jerk, lateral acceleration, steering speed) between the Bloss curve and more traditional curves, such as clothoid and Generalized Cornu Spirals (GCS). Nine case studies were conducted, each case was characterized considering the type of transition curve used (clothoid, GCS and Bloss curve) and radius R of the exit curve (R = 60 m, 80 m, 100 m). The numerical values assumed by the kinematic variables along the transition curves were "locally" calculated, i.e. "pointby- point", to take into account the non-uniform motion regime. The results obtained, limited to the cases studied, show that the Bloss curve better meets the kinematic conditions of the vehicle motion in non-uniform driving regimes. Therefore, the Bloss curve can be considered as a braking curve in the design of road intersections and be a candidate for further investigation to assess any additional benefits in terms of comfort, driving safety and visual perception of the geometric element

Correction to: The vibrations induced by surface irregularities in road pavements – a Matlab® approach

fter publication of this article [1], it is noticed the article contained an error with eq. 12, the c s should be squared. The correct eq. 12 is provided below Document type: Articl

Trapping in irradiated p-on-n silicon sensors at fluences anticipated at the HL-LHC outer tracker

The degradation of signal in silicon sensors is studied under conditions expected at the CERN High-Luminosity LHC. 200 $\mu$m thick n-type silicon sensors are irradiated with protons of different energies to fluences of up to $3 \cdot 10^{15}$ neq/cm$^2$. Pulsed red laser light with a wavelength of 672 nm is used to generate electron-hole pairs in the sensors. The induced signals are used to determine the charge collection efficiencies separately for electrons and holes drifting through the sensor. The effective trapping rates are extracted by comparing the results to simulation. The electric field is simulated using Synopsys device simulation assuming two effective defects. The generation and drift of charge carriers are simulated in an independent simulation based on PixelAV. The effective trapping rates are determined from the measured charge collection efficiencies and the simulated and measured time-resolved current pulses are compared. The effective trapping rates determined for both electrons and holes are about 50% smaller than those obtained using standard extrapolations of studies at low fluences and suggests an improved tracker performance over initial expectations

Characterisation of irradiated thin silicon sensors for the CMS phase II pixel upgrade

The high luminosity upgrade of the Large Hadron Collider, foreseen for 2026, necessitates the replacement of the CMS experiment's silicon tracker. The innermost layer of the new pixel detector will be exposed to severe radiation, corresponding to a 1 MeV neutron equivalent fluence of up to Phi(eq) = 2x10(16) cm(-2), and an ionising dose of approximate to 5 MGy after an integrated luminosity of 3000 fb(-1). Thin, planar silicon sensors are good candidates for this application, since the degradation of the signal produced by traversing particles is less severe than for thicker devices. In this paper, the results obtained from the characterisation of 100 and 200 mu m thick p-bulk pad diodes and strip sensors irradiated up to fluences of Phi(eq) = 1.3 x 10(16) cm(-2) are shown.Peer reviewe

Description and performance of track and primary-vertex reconstruction with the CMS tracker

A description is provided of the software algorithms developed for the CMS tracker both for reconstructing charged-particle trajectories in proton-proton interactions and for using the resulting tracks to estimate the positions of the LHC luminous region and individual primary-interaction vertices. Despite the very hostile environment at the LHC, the performance obtained with these algorithms is found to be excellent. For tbar t events under typical 2011 pileup conditions, the average track-reconstruction efficiency for promptly-produced charged particles with transverse momenta of pT > 0.9GeV is 94% for pseudorapidities of |η| < 0.9 and 85% for 0.9 < |η| < 2.5. The inefficiency is caused mainly by hadrons that undergo nuclear interactions in the tracker material. For isolated muons, the corresponding efficiencies are essentially 100%. For isolated muons of pT = 100GeV emitted at |η| < 1.4, the resolutions are approximately 2.8% in pT, and respectively, 10μm and 30μm in the transverse and longitudinal impact parameters. The position resolution achieved for reconstructed primary vertices that correspond to interesting pp collisions is 10–12μm in each of the three spatial dimensions. The tracking and vertexing software is fast and flexible, and easily adaptable to other functions, such as fast tracking for the trigger, or dedicated tracking for electrons that takes into account bremsstrahlung

P-Type Silicon Strip Sensors for the new CMS Tracker at HL-L-HC

Abstract: The upgrade of the LHC to the High-Luminosity LHC (HL-LHC) is expected to increase the LHC design luminosity by an order of magnitude. This will require silicon tracking detectors with a significantly higher radiation hardness. The CMS Tracker Collaboration has conducted an irradiation and measurement campaign to identify suitable silicon sensor materials and strip designs for the future outer tracker at the CMS experiment. Based on these results, the collaboration has chosen to use n-in-p type silicon sensors and focus further investigations on the optimization of that sensor type

Superpave® mix design method of recycled asphalt concrete applied in the european standards context.

The recycling of road and airport asphalt pavements requires greater reliability of mix design in order to ensure proper rehabilitation and effective reuse of recycled asphalt concrete. Currently, internationally, the most effective mix design procedures for recycled asphalt concrete with RAP (Reclaimed Asphalt Pavement) refer to guidelines developed by SuPerPave® Mixtures Expert Task Group. In this paper, according to the requirements of the European standard EN 13108, the authors investigated the reliability of the above mix design procedure. In particular, the SuPerPave® mix design guidelines were applied for dosing components of wearing course layer recycled asphalt mixture and for the determination of PG (Performance Grade) and critical temperatures of binder contained in RAP (RAP binder) and of binder added ex-novo (virgin binder). The experimental research program started from RAM (Reclaimed Aggregate Material) grading characterization and RAP binder content determination. Afterwards, rheological characterization of the RAP binder and selected virgin binder was carried out using the DSR (Dynamic Shear Rheometer) and BBR (Bending Beam Rheometer) devices. This step allowed us to identify the right virgin binder percentages to be added to RAP binder. Then, in compliance with European standards, the mix design study of recycled mixtures was carried out, identifying the necessary granulometric integrations and the virgin-binder-appropriate percentages to be added. In this phase, three different RAP percentages were used: 30%, 40%, and 50%. Finally, the experimental plan was completed with a preliminary mechanical characterization of the studied recycled asphalt mixtures. The results showed that the implemented rational mix design guarantees performance levels of wearing course layer recycled mixtures that are fully in compliance with European standards