Numerical and Experimental Analysis of the Pressure Signature for different High-Speed Trains

This paper describes a procedure for the validation of numerical codes able to reproduce the pressures in tunnel due to the passage of trains. In the first step, the parameters of the numerical code are set by matching the train-tunnel pressure signature measured during a single-passage of different types of train within the tunnel and in the second step, without changing the parameters, the crossing of two trains is simulated. Within the paper, the methodology is applied to the numerical mono-dimensional code DB-Tunnel while the experimental data are those collected during an experimental research programme carried out in the tunnel La Fornace, on the Italian high-speed railway from Roma to Firenze. The accuracy of the numerical code estimation is evaluated in terms of the maximum pressure generated in the tunnel by the train passing/crossing because this is the key parameter, according to the TSI standard for railway infrastructures

Simplified estimation of the train resistance parameters: full scale experimental tests and analysis

A CEN standard (EN 14067-4, 2005) describes the methodologies for the assessment of the running resistance of railway vehicles starting from full-scale test measurements. According to this standard, the speed dependent terms of the equation of Davis [1] have to be determined by means of coasting tests. In this paper, a new method to estimate the running resistance coefficients from a full-scale coasting test is proposed and compared with the two methods proposed in the CEN standard (the regression method and the speed history identification method). The main advantage of this new method is that it does not require the railway line characteristics to be known and it will be shown that the new method is able to evaluate the coefficients with an accuracy equivalent to that of the other methods considered

Old Age and Aerobic Microorganisms of Patients Affected by Clostridium difficile Infection are Associated Primarily with the Intestinal Presence of Clostridium difficile

Clostridium difficile infection in human occurs when the organism is present and germinating in the bowel. Old age of patients\u2019 and particular microorganisms in stools are identified as risk factors for the disease onset. We aimed to investigate if risk factors for C. difficile infections in a large Italian hospital were connected to C. difficile intestinal presence or to germination. Toxin B positivity was linked with age over 65 years (P=0.03), medical hospitalization (P=0.015) and growth of Enterobacteriaceae (P=0.029) and Enterococcus (P=0.05) from the same stools. The presence of tcdB was even more strictly linked with old age (P=0.005), medicine hospitalization (P=0.012) and growth of Enterobacteriaceae (P=0.003) and Enterococcus (P=0.04). Our results indicated that the presence of C. difficile in stools, irrespective of being spore or vegetative form, is reliably associated with old age of subjects and fecal presence of viable Enterobacteriaceae and Enterococcus

Aerodynamic loads in open air of high speed trains: Analysis of experimental data

The homologation of high-speed trains is a demanding and expensive procedure. In particular, the evaluation of train slipstream according to the standard TSI, 2008 is divided in two different test programmes: one concerning the workers at the trackside and the other studying the passengers standing on the platform. This paper presents some slipstream measurements performed on three high speed trains and a comparison between them. The objective is to investigate the slipstream on the platform and relate it to the flow measured at the trackside at the same height with respect to the top of the rail. This topic is currently under revision by the commission in charge of the TSI standard. Interesting evidence concerning the improvements of the aerodynamic performance of new-generation trains are highlighted

Ballast flight under high-speed trains: Wind tunnel full-scale experimental tests

The flying ballast phenomenon has become an important problem, in the last years, because of the development of high speed trains and the consequent increase of the speed up to 350. km/h. The problem is very complex since it is related to both railway infrastructure and train characteristics and since it involves mechanical and aerodynamic effects. The results of an experimental study carried out on the Italian high-speed railway and on a 1:1 real stretch of the railways in wind tunnel are presented in the paper. The study was aimed to analyze the effects of the height of the ballast level, the stone shape in the upper layer of the ballast and the compaction of the ballast bed on the problem. To this purpose a specific wind tunnel test rig was designed to reproduce in the wind tunnel a flow with the same average characteristics of the one measured on the real line, especially in the region close to the ballast and sleepers. Finally, starting from the results of these tests, possible countermeasures to ballast lifting on-set are proposed

The complex hodological architecture of the macaque dorsal intraparietal areas as emerging from neural tracers and dw-mri tractography

In macaque monkeys, dorsal intraparietal areas are involved in several daily visuomotor actions. However, their border and sources of cortical afferents remain loosely defined. Combining retrograde histologic tracing and MRI diffusion-based tractography, we found a complex hodology of the dorsal bank of the intraparietal sulcus (db-IPS), which can be subdivided into a rostral intraparietal area PEip, projecting to the spinal cord, and a caudal medial intraparietal area MIP lacking such projections. Both include an anterior and a posterior sector, emerging from their ipsilateral, gradient-like connectivity profiles. As tractography estimations, we used the cross-sectional area of the white matter bundles connecting each area with other parietal and frontal regions, after selecting regions of interest (ROIs) corresponding to the injection sites of neural tracers. For most connections, we found a significant correlation between the proportions of cells projecting to all sectors of PEip and MIP along the continuum of the db-IPS and tractography. The latter also revealed “false positive” but plausible connections awaiting histologic validation

Codes and standards on computational wind engineering for structural design: State of art and recent trends

This paper first provides a wide overview about the design codes and standards covering the use of Computational Wind Engineering / Computational Fluid Dynamics (CWE/CFD) for wind-sensitive structures and built environment. Second, the paper sets out the basic assumptions and underlying concepts of the new Annex T "Simulations by Computational Fluid Dynamics (CFD/CWE)" of the revised version "Guide for the assessment of wind actions and effects on structures" issued by the Advisory Committee on Technical Recommendations for Constructions of the Italian National Research Council in February 2019 and drafted by the members of the Special Interest Group on Computational Wind Engineering of the Italian Association for Wind Engineering (ANIV-CWE). The same group is currently advising UNI CT021/SC1 in supporting the drafting of the new Annex K - "Derivation of design parameters from wind tunnel tests and numerical simulations" of the revised Eurocode 1: Actions on structures - Part 1-4: General actions - Wind actions. Finally, the paper outlines the subjects most open to development at the technical and applicative level

Low-Temperature Fluorocarbonate Mineralization in Lower Devonian Rhynie Chert, UK

Funding: J.G.T.A was partially funded by the Natural Environment Research Council, grant number NE/T003677/1. Acknowledgments: We are grateful to W. Ritchie, J. Johnston, and J. Bowie for skilled technicalsupport. Samples were archived by N.H. Trewin, C.M. Rice and S. Fayers.Peer reviewedPublisher PD