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This paper studies the evolvement of the wear irregularity of contact wire using wire thickness data measured yearly from a section of railway catenary. The power spectral density and time-frequency representation based on the wavelet transform are employed for data analysis, with an emphasis on local wear irregularities that are crucial for contact wire condition assessment. To investigate the cause of wear irregularity evolvement and the mutual influence with the pantograph-catenary dynamic interaction, simulations considering the influence of wear irregularity are carried out based on the finite element method. Analyses of the actual wear irregularities and the dynamic contact force under singular and complex wear irregularities are performed. Although the wear irregularity has limited impact on the pantograph-catenary interaction, it can induce the vibration of pantograph and contact wire that will lead to a notable increase of contact force standard deviation. The evolvement of wear irregularity is closely associated with the span length and dropper distribution of catenary structure and the running direction of pantograph. In addition, it is found feasible to detect the wear irregularity based on contact force, on condition that the sampling frequency is high enough to reflect the indicative frequencies. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the capability of an axle box acceleration (ABA) system to evaluate the degradation at railway crossings. For this purpose, information from multiple sensors, namely, ABA signals, 3D rail profiles, Global Positioning System (GPS) and tachometer recordings, was collected from both nominal and degraded crossings. By proper correlation of the gathered data, an algorithm was proposed to distinguish the characteristic ABA related to the degradation and then to evaluate the health condition of crossings. The algorithm was then demonstrated on a crossing with an unknown degradation status, and its capability was verified via a 3D profile measurement. The results indicate that the ABA system is effective at monitoring two types of degradations. The first type is uneven deformation between the wing rail and crossing nose, corresponding to characteristic ABA frequencies of 230-350 and 460-650 Hz. The second type is local irregularity in the longitudinal slope of the crossing nose, corresponding to characteristic ABA frequencies of 460-650 Hz. The types and severity of the degradation can be evaluated by the spatial distribution and energy concentration of the characteristic frequencies of the ABA signals. [ABSTRACT FROM AUTHOR]

A three-dimensional (3D) finite element (FE) dynamic frictional rolling contact model is presented for the study of short pitch corrugation that considers direct and instantaneous coupling between the contact mechanics and the structural dynamics in a vehicle-track system. In this study, we examine the system responses in terms of vibration modes, contact forces and the resulting wear with smooth rail and corrugated rail with progressively increasing amplitude to infer the conditions for consistent corrugation initiation and growth. Wear is assumed to be the damage mechanism, and short pitch corrugation is modeled using wavelengths from field observations of a Dutch railway. The contribution of this paper is a global perspective of the consistency conditions that govern the evolution of short pitch corrugation. The main insights are as follows: (1) the longitudinal vibration modes are probably dominant for short pitch corrugation initiation; (2) during short pitch corrugation evolution, the interaction and consistency between longitudinal and vertical modes should determine the development of short pitch corrugation, and once a certain severity is reached, vertical modes become dominant; and (3) in the case simulated in this paper, corrugation does not grow probably due to not only the different resulting main frequencies of the vertical and longitudinal contact forces, but also the inconsistency between the frequencies of the vertical and longitudinal vibration modes and the resulting wear. It is inferred that in the continuous process of initiation and growth of the corrugation, there should be a consistency between them, and this could be done by the control of certain track parameters. [ABSTRACT FROM AUTHOR]

This paper presents a study of the parameters that influence the detection of squats when using axle box acceleration (ABA) measurements. The analysed parameters include the train speed, the location of the squat in the track relative to the sleeper, and the track design. The study is conducted relying on a validated finite element model. The ABA measurements are found to be highly influenced by train speed. To model this influence, a practical method is proposed to represent the relationship between the train speed and relevant characteristics of ABA (magnitude and frequency) at a given squat. Such practical relationships provide the opportunity to map the ABA signals when it proves impossible to run measuring trains at a constant speed (as is the case with any in-service railway vehicle). The parameter study also indicates that the major frequency characteristics of ABA at squats are strongly related to the natural frequencies of the track. This conclusion is validated by performing hammer tests on the railway track. It is suggested that a proper characterization of the tracks will lead to a better understanding of the ABA signals. Finally, it is claimed that the results presented in this paper can be used as a guideline to calibrate or improve squat detection algorithms based on ABA measurements on a track. [ABSTRACT FROM AUTHOR]

Observational, descriptive and prospective pharmacovigilance study, based on the active investigation of suspected adverse drug reactions in patients admitted to a pediatric intensive care unit between July 2009 and June 2010 for characterizing them according to age, sex, drug group, suspected drug affecting organ systems, causality, mechanism of production and frequency of occurrence. Complementarily, the incidence of such reactions and the occupancy rate per affected patient were calculated. Adverse reactions occurred in 11.2% of children, being more frequent between the first and fourth years of age (31.0%) and in males (64.2%). The predominant pharmacological group was related with the anti-infective drugs for systemic use (69%) and appeared mostly associated with the administration of oseltamivir. Hypokalemia and skin rash were detected for furosemida and vancomycin (31% each). There were 64.3% of potential reactions as causality, a predominance of common reactions (52.4%) and 52.4% were classified as B in accordance with the mechanism. Most of adverse reactions were mild (71.4%), the occupancy rate was 3.1 and incidence of those reactions reached 0.044. Despite serious child belongs to a high-risk population group, adverse events did not reveal as alarming and mostly matched with those already described for the reported medications. Exceeding these considerations, this type of study allows identifying and preventing such reactions for choosing the corresponding preventive actions. [ABSTRACT FROM AUTHOR]

• Optimal Lithium-ion battery sizing for hybrid diesel-electric train is presented. • Bi-level optimization approach integrates optimal sizing and control levels. • Two energy management strategies are developed and compared. • Trade-off between fuel savings and hybridization cost is analyzed. • Fuel savings and CO 2 emissions reduction of up to 34.5% is obtained. Hybridization of diesel multiple unit railway vehicles is an effective approach to reduce fuel consumption and related emissions in regional non-electrified networks. This paper is part of a bigger project realized in collaboration with Arriva, the largest regional railway undertaking in the Netherlands, to identify optimal solutions in improving trains' energy and environmental performance. A significant problem in vehicle hybridization is determining the optimal size for the energy storage system, while incorporating an energy management strategy as well as technical and operational requirements. With the primary requirement imposed by the railway undertaking to achieve emission-free and noise-free operation within railway stations, we formalize this as a bi-level multi-objective optimization problem, including vehicle performance, the trade-off between fuel savings and hybridization cost, influence of the energy management strategy, and other constraints. By deriving a Li-ion battery parameters at the cell level, a nested coordination framework is employed, where a brute force search finds the optimal battery size using dynamic programming for full controller optimization for each feasible solution. In this way, the global minimum for fuel consumption for each battery configuration is achieved. The results from a Dutch case study demonstrated fuel savings and CO 2 emission reduction of more than 34% compared to a standard vehicle. Additionally, benefits in terms of local pollutants (NO x and PM) emissions are observed. Using an alternative sub-optimal rule-based control demonstrated a significant impact of the energy management on the results, reflected in higher fuel consumption and increased battery size together with corresponding costs. [ABSTRACT FROM AUTHOR]

This paper proposes a novel framework for simulating the dynamics of beams on elastic foundations. Specifically, partial differential equations modeling Euler–Bernoulli and Timoshenko beams on the Winkler foundation are simulated using a causal physics-informed neural network (PINN) coupled with transfer learning. Conventional PINNs encounter challenges in handling large space–time domains, even for problems with closed-form analytical solutions. A causality-respecting PINN loss function is employed to overcome this limitation, effectively capturing the underlying physics. However, it is observed that the causality-respecting PINN lacks generalizability. We propose using solutions to similar problems instead of training from scratch by employing transfer learning while adhering to causality to accelerate convergence and ensure accurate results across diverse scenarios. The primary contribution of this paper lies in introducing a causality-respecting PINN loss function in the context of structural engineering and coupling it with transfer learning to enhance the generalizability of PINNs in simulating the dynamics of beams on elastic foundations. Numerical experiments on the Euler–Bernoulli beam highlight the efficacy of the proposed approach for various initial conditions, including those with noise in the initial data. Furthermore, the potential of the proposed method is demonstrated for the Timoshenko beam in an extended spatial and temporal domain. Several comparisons suggest that the proposed method accurately captures the inherent dynamics, outperforming the state-of-the-art physics-informed methods under standard L 2 -norm metric and accelerating convergence. [ABSTRACT FROM AUTHOR]

This study evaluates the degradation of wheels and rails at railway crossings. The evaluation method is composed of 1) finite element simulation of dynamic wheel/crossing interaction and 2) multi-criteria analysis of wheel/rail degradation in terms of yield behavior, rolling contact fatigue (RCF) and wear. With the aid of this method, we conducted a case study identifying the proper yield strength of rail steel material for a 54E1-1:9 crossing under a specified traffic condition. The case study indicates that the wear of contact bodies is more sensitive to train speed compared with yield and RCF; the increase of rail yield strength suppresses rail degradation while exacerbating wheel degradation; and rail yield strength in the range of 500–600 MPa is preferred to achieve a good trade-off between the wheel and rail degradations. • A method is proposed to evaluate the degradation of wheels and rails at railway crossings. • The method uses finite element simulation and multi-criteria analysis. • Wheel/rail degradation is evaluated in terms of yield behavior, rolling contact fatigue (RCF) and wear. • A case study is conducted to identify the proper yield strength of rail steel material for a 54E1-1:9 crossing. [ABSTRACT FROM AUTHOR]