Comparison of Braking Performance for Different Technologies of Heavy Hauled Freight Trains

The paper shows a comparison of different braking technologies for freight trains and their effects on in-train forces. At this aim, the UIC certified software TrainDy is employed. Freight train sets, having one and two remote locomotives, are investigated both as coupled trains and as fixed train compositions. There is also an evaluation of the in-train forces of freight train sets equipped by electro-pneumatic brakes and disk brakes. The case of two remote locomotives is further explored showing the minor benefits of an ad hoc activation of drivers brake valve, compared to the benefits of an optimized mass distribution, for train sets both coupled and fixed

The Train dynamics of wheel rail contact and longitudinal lateral interaction between vehicles

This paper is focused on the vehicle dynamics caused by the forces exchanged, through buffers and draw gears, by consecutive vehicles on a curve. The results have been obtained by adding a buffers/draw gears contact model on an existing multibody code, previously developed by the authors. The multibody code manages rigid bodies connected by elastic and rigid constraints; the wheel/rail contact model is three dimensional and employs an elastic constraint among wheel and rail. The wheel/rail contact is managed by means of a numerical model called TOAM (third order approximation method). Numerical tests and experimental validations of the proposed model are here presented, considering a train made by three vehicles, running on an S shaped curve, subjected to parametric compressive forces

Effective ways to compare two families of freight trains

The paper shows several use cases of the "relative approach" method, envisaged by international recommendations, for evaluating the safety of two families of freight trains. This is relevant when a decision is needed about a new technology or a new operating mode of freight trains to keep the same safety as existing trains. The paper discusses the heterogeneity of the database of trains and provides examples of the classic application of the "relative approach", highlighting the effect of train operation. Furthermore, it shows the application to DAC and radio-controlled Traction Units. Finally, it introduces the "Iterative Proportional" algorithm to generate a freight train from an existing one just by changing the hauled mass of each wagon. This algorithm is helpful when the "relative approach" is applied to trainsets having articulated wagons and running with a similar braking regime

A statistical study on long freight trains equipped with radio communication within Shift2Rail

Paper reports the main results of a systematic study on longitudinal train dynamics (LTD) of long freight trains equipped with radio communication. It is divided in two parts: the first addresses the global sensitivity analysis aiming to find the most relevant parameters that, with their associated uncertainty, mainly affect the LTD of coupled trains, independently by the train length or train operation. The second part studies the LTD of classic freight trains in Germany (i.e. with one Traction Unit -TU- at the beginning of the train), considering the variation of the parameters identified during the sensitivity analysis. Finally, several train-consists with two up to four TU and having train length up to 1500 m are found to be as safe as the classic trains and therefore can put in service, as long as the LTD is concerned, allowing a relevant increase of efficiency

LARES/WEBER-SAT and the equivalence principle

It has often been claimed that the proposed Earth artificial satellite LARES/WEBER-SAT-whose primary goal is, in fact, the measurement of the general relativistic Lense-Thirring effect at a some percent level-would allow to greatly improve, among (many) other things, the present-day (10^-13) level of accuracy in testing the equivalence principle as well. Recent claims point towards even two orders of magnitude better, i.e. 10^-15. In this note we show that such a goal is, in fact, unattainable by many orders of magnitude being, instead, the achievable level of the order of 10^-9.Comment: LaTex, 4 pages, no figures, no tables, 26 references. Proofs corrections included. To appear in EPL (Europhysics Letters

Simulation of freight trains with up to three traction units in radio communication

Paper reports the main results of a systematic study on longitudinal train dynamics (LTD) of long freight trains, equipped with radio communication. The simulation results have been used to prepare an experimental test campaign to test the Distributed Power System (DPS) technology. The simulations refer to up/down and level track and they compare the LTD of trains with and without DPS, for different train operations and radio link conditions. The DPS technology is proved (by simulations and test) to be a very effective way to increase the efficiency of future freight trains

A yeast synthetic network for in-vivo assessment of reverse engineering and modelling.

Systems biology approaches are extensively used to model and reverse engineer gene regulatory networks from experimental data. Conversely, synthetic biology allows ‘‘de novo’’ construction of a regulatory network to seed new functions in the cell. At present, the usefulness and predictive ability of modeling and reverse engineering cannot be assessed and compared rigorously. We built in the yeast Saccharomyces cerevisiae a synthetic network, IRMA, for in vivo ‘‘benchmarking’’ of reverse-engineering and modeling approaches. The network is composed of five genes regulating each other through a variety of regulatory interactions; it is negligibly affected by endogenous genes, and it is responsive to small molecules. We measured time series and steady-state expression data after multiple perturbations. These data were used to assess state-of-the-art modeling and reverse-engi- neering techniques. A semiquantitative model was able to capture and predict the behavior of the network. Reverse engineering based on differential equations and Bayesian networks correctly inferred regulatory interactions from the experimental data

Cholesteatoma vs granulation tissue: a differential diagnosis by DWI-MRI apparent diffusion coefficient

To diagnose cholesteatoma when it is not visible through tympanic perforation, imaging techniques are necessary. Recently, the combination of computed tomography and magnetic resonance imaging has proven effective to diagnose middle ear cholesteatoma. In particular, diffusion weighted images have integrated the conventional imaging for the qualitative assessment of cholesteatoma. Accordingly, the aim of this study was to obtain a quantitative analysis of cholesteatoma calculating the apparent diffusion coefficient value. So, we investigated whether it could differentiate cholesteatoma from other inflammatory tissues both in a preoperative and in a postoperative study