M. Catelani, L. Ciani, R. Singuaroli, A. Mannucci
Electrolytic Capacitor Lifetime Prediction in Ground Mobile Applications

Electrolytic capacitors are widely used in several power electronic systems. Their high energy density (J/cm³) features make them an attractive candidate for smoothing voltage ripple in supply circuitry. However, electrolytic capacitors have the shortest life span of components in power electronic circuits, usually due to their wear-out failure. The main wear-out mechanisms in electrolytic capacitors are the loss of the electrolyte by vapor diffusion trough the seals and the deterioration of the electrolyte. In this paper, a corrective model for reliability prediction is presented. This model is employed satisfactorily to estimate lifetime duration according to manufacturers’ tests. An implementation of this method is proposed, which can be very helpful for predicting the capacitor reliability and alerting plant operators to execute maintenance and/or replacement of the component.

Zygmunt Warsza, Adam Idzkowski, Wojciech Walendziuk
Unconventional double-current circuit – accuracy measures and application in two-parameter measurement

In this paper some interesting and novel features of a four-terminal (4T) network are presented. A single DC current source is switched over and connected in turns to opposite arms of the four-element bridge circuit. This two-voltage-output circuit is called a double current bridge. The output voltages are dependent on the arm resistance increments and their values are given in absolute and relative units. The accuracy measures (limited errors and standard uncertainties) of two transfer functions are presented. A simple application with two sensors acting as strain gauges and RTD’s is presented. The simplified signal conditioning formulas of two- parameter measurement of strain and temperature of a cantilever beam are discussed. Some results achieved with the use of the circuit are presented.

Marta Wisniewska, Sabina Zebrowska-Lucyk
Toward improved performance in separation of roughness, waviness and form: ISO 16610 series

During recent years the surface texture measurement and analysis has become one of the most important fields of interest in modern metrology. So, the development of the new filtering methods, enabling to separate surface’s components of different scale, should not be surprising. However, Gaussian linear filter, in spite of its significant drawbacks, remains the one and the only filter used by the vast majority of engineers in their professional performance. It is a result both of the chaos brought by the dozens of filtration algorithms proposed recently and the low consciousness of their advantages over the typical filters. Due to this, the ISO 16610 standard series has been devised. Its main aim is to promote recent advances in the surface texture filtration techniques and systematise knowledge about them. This paper reviews the set of standards concerning the profile (2D) filters discussed in this series: Gaussian, spline, wavelet and morphological ones. It also outlines main features and possible applications of these filtration algorithms.

D. Macii, S. Dalpez, M. Avancini, L. Benciolini, M. Corrà, R. Passerone
A Safety System for Zero Velocity Detection and Operator Alertness Monitoring in Rolling Stock

Modern railroad applications must fulfill proper reliability, availability, maintainability and safety (RAMS) specifications in compliance with the requirements of widely accepted international standards such as EN 50126-1:1999 and EN 50126-2:2007. In rolling stock two complementary hazards with potential critical consequences for passengers and personnel arise from the inability to determine if a vehicle is in motion and from the inability to detect if the operator driving the train is incapacitated. While the probability of occurrence of both events is remote, the level of risk of such hazards is generally not tolerable. To assure an adequate safety integrity level (SIL) depending on the target application, ad-hoc smart monitoring systems, typically referred to as dead-man's vigilance devices (DMVD), are generally installed on board of rolling stocks. In this paper the safety analysis and the design procedure of a novel DMVD are described. The main elements of novelty of the proposed solution lay in its implementation, which relies on a hardware-only, potentially redundant FPGA architecture.

Marcin Steczek, Adam Szelag
On-line measurements of input impedance of an electric traction vehicle supplied by DC catenary for identification and reduction of disturbances in signalling and control track circuits

The use of power electronics in modern drive systems that are used for traction purposes, makes it necessary to conduct EMC control regarding disturbances in operation of other devices of railway infrastructure that are caused by the vehicles, especially in traffic and signalling management systems. One of the investigated parameters is the value of input impedance of a vehicle. The article presents the results of works on analysis of traction vehicles input impedance as well as impedance measurements under laboratory conditions. The possibility of on-line measurements of impedance in vehicles operating conditions was discussed, the use of these results in a diagnostics system measuring the level of disturbances from higher harmonics introduced by a vehicle into the rail network were also presented. One proposed application of an algorithm enabling introduction of the changes of the manner of control of a vehicle's drive system, while maintaining the required torque that is developed by the vehicle's motors, but at the lowest level of introduced disturbances.