1,721,139 research outputs found
New random trains generation according to UIC code 421
Full text linkThis paper illustrates a new method to generate random trainsets, compliant with UIC CODE 421, which is the common standard followed by Railway Undertakings in Europe for international freight traffic. Random generation of trains is an important topic for risk assessment of new train composition, which is of particular interest in this period in Europe. In fact, there are several studies on new types of trains with distributed traction/braking that require a statistical assessment of Longitudinal Train Dynamics (LTD). Results reported in this paper show that the new method represents more accurately the target payload distribution of real wagons, with respect to the standard method currently proposed by the UIC CODE 421. The new algorithm is suitable for the revision of UIC CODE 421, as a novel way to generate random trains
Effective ways to compare two families of freight trains
Full text linkThe 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
Non-standard applications of the IRS 40421 methodology
No full textThis paper shows three non-standard applications of the “relative approach” envisaged by the International Railway Solution IRS 40421: this document imposes some restrictions on the mass and length of interoperable freight trains, but it also provides a methodology for admitting to the traffic trains that exceed these limits. The paper considers the case of a single train, a family of trains with a new brake position and an optimized wagon order
Effetti dinamici secondo la ISO 6336 ed un modello a rigidezza distribuita dell’ingranaggio
No full textA study on releasing manoeuvre to improve freight safety and efficiency
Full text linkThe paper investigates the in-train tensile forces that occur during a braking manoeuvre followed by brake release and train acceleration. More in detail, it analyses the effect of traction unit characteristics, in terms of power application gradient and time of power application, on highest in-train tensile forces, for different braking and releasing regimes. By taking into consideration both uniformly and not-uniformly loaded trains, it is shown that it is possible to significantly increase freight efficiency, also avoiding train disruption risk, by smoothly applying power to traction unit just after the initiation of brake releasing operation
Percorsi strategici per lo sviluppo del sistema di telecomunicazioni in Campania. Un'agenda di lavoro per gli stakeholder
No full textA simplified pneumatic model for air brake of passenger trains
Full text linkBraking 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
Percorsi strategici per lo sviluppo del sistema di telecomunicazioni in Campania. Un'agenda di lavoro per gli stakeholder
No full textModelli monodimensionali alle differenze finite per lo studio termico della frenatura dei treni
No full textTra i sistemi di un treno quello della frenatura ha la maggiore importanza sulla sicurezza. Questo articolo si concentra sulle principali tipologie di freni utilizzate in questo contesto: ceppi e dischi. Essendo il loro principio di funzionamento legato all’attrito, la temperatura degli elementi in contatto deve essere tenuta sotto controllo, al fine di prevenire una loro rottura improvvisa durante l'utilizzo, che causa un aumento degli spazi d’arresto e, in caso di rottura della ruota, potrebbe condurre anche ad un deragliamento del treno. Per riuscire a modellare numericamente la temperatura negli elementi d’attrito dei freni ferroviari, l'articolo presenta due modelli 1D basati sulle Differenze Finite (DF) per entrambe le tipologie di freno. Nel caso dei ceppi, il modello considera la coordinata radiale, mentre per i dischi si utilizza quella assiale; in entrambi i casi, lungo queste coordinate si hanno le maggiori variazioni di temperatura. Per i dischi, in particolare, il modello 1D equivalente sviluppato è anche in grado di tener conto della ventilazione, nonostante la sola coordinata considerata. Successivamente, l’articolo si focalizza sull’importanza di simulare gli effetti termici sul coefficiente d’attrito tenendo in considerazione la dinamica longitudinale; a questo fine, il modello è stato inserito in TrainDy per effettuare questo studio in maniera accoppiata
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