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

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 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

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

A Model of Control Valve for Wagons Equipped by k-Blocks

Paper illustrates the key features of the control valve model of TrainDy, renewed to be compliant with wagons that equip composite brake blocks type k in their braking systems. TrainDy is an international software owned by UIC (The International Union of Railways) and used by major Railway Undertakings in Europe to perform computations of Longitudinal Train Dynamics. Composite brake blocks type k equips new or revamped freight trains in Europe and are used to reduce train noise caused by particles of friction material between wheel and rail. This topic is particularly relevant since a relevant part of freight traffic in Europe is performed during night and many railway lines are close to highly populated areas. Paper shows the validation of this new model against experimental test campaigns performed at bench and in real field and made available for the revision process of UIC CODE 421 for freight train interoperability

‘Movement as disclosive of being’ Merleau-Ponty: from the psychology of gestalt to the analysis of movement

In this essay we seek to clarify the meaning and theoretical implications of the statement by Merleau-Ponty contained in his 1953 course, Le Monde Sensible et le Monde de l’Expression, according to which movement is ‘revealing of being’. This analysis takes up and comments on chapter 7 of Koffka’s Principles of Gestalt Psychology (dedicated to the issue of movement) and related experiments in particular. We will show that Merleau-Ponty’s idea of ontology of movement emerges from his examination of several exemplary cases. This method of analysis brings to light an idea of similar phenomenology compatible with an experimental phenomenolog

A simplified pneumatic model for air brake of passenger trains

Braking system performance is relevant for both railway safety and network optimization. Most trains employ air brake systems; air brake systems of freight trains mostly cannot achieve a synchronous application of brake forces, which is usually customary for passenger trains. The paper generalizes a previous air brake pneumatic model to passenger trains and describes the needed modifications. Among them, the way the pressure reduces in the brake pipe is generalized. Moreover, this paper reports an analytical bi-dimensional function for calculating the nozzle diameter equivalent to the electro-pneumatic (EP) or the electronically controlled pneumatic (ECP) brake valve as a function of the wagon length and the time to vent the brake pipe locally. The numerical results of the new model are compared against several experimental tests of high-speed passenger trains of Trenitalia, namely ETR500 and ETR1000. The model is suitable to be integrated into the UIC software TrainDy, aiming to extend its computational field to passenger trains and to simulate the safety of trains during a recovery

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

A Brief History of Singlefold Diophantine Definitions

Consider an (m + 1)-ary relation R over the set N of natural numbers. Does there exist an arithmetical formula ZΘ(a0, . . . , am, x1, . . . , xK), not involving universal quantifiers, negation, or implication, such that the representation and univocity conditions, viz., (Formula Presented) are met by each tuple (Formula Presented). A priori, the answer may depend on the richness of the language of arithmetic: Even if solely addition and multiplication operators (along with the equality relator and with positive integer constants) are adopted as primitive symbols of the arithmetical signature, the graph R of any primitive recursive function is representable; but can representability be reconciled with univocity without calling into play one extra operator designating either the dyadic operation [b, n]↠ b n or just the monadic function n ↠ b n associated with a fixed integer b > 1? As a preparatory step toward a hoped-for positive answer to this question, one may consider replacing the exponentiation operator by a dyadic relator designating an exponential-growth relation (a notion made explicit by Julia Bowman Robinson in 1952). We will discuss the said univocity, aka ‘single-fold-ness’, issue-first raised by Yuri V. Matiyasevich in 1974-, framing it in historical context. © 2023 Copyright for this paper by its authors