In embarking towards Cyber-Physical Systems (CPS) with unprecedented capabilities it becomes essential to improve our understanding of CPS complexity and how we can deal with it. We investigate facets of CPS complexity and the limitations of Collaborating Information Processing Systems (CIPS) in dealing with those facets. By CIPS we refer to teams of humans and computer-aided engineering systems that are used to develop CPS. Furthermore, we specifically analyze characteristic differences among software and physical parts within CPS. The analysis indicates that it will no longer be possible to rely only on architectures and skilled people, or process and model/tool centered approaches. The tight integration of heterogeneous physical, cyber, CPS components, aspects and systems, results in a situation with interfaces and interrelations everywhere, each requiring explicit consideration. The role of modelbased and computer aided engineering will become even more essential, and design methodologies will need to deeply consider interwoven systems and software aspects, including the hidden costs of software.

The current study investigates the characteristics of particles generated from the wear of braking materials, and provides an applicable index for measuring and comparing wear particle emissions. A pin-on-disc tribometer equipped with particle measurement instruments was used. The number concentration, size, morphology, and mass concentration of generated particles were investigated and reported for particles 10 nm to 32 µm in diameter. The particles were also collected on filters and investigated using EDS and SEM. The effects of wear mechanisms on particle morphology and changes in particle concentration are discussed. A new index, the airborne wear particle emission rate (AWPER), is suggested that could be used in legislation to control non-exhaust emissions from transport modes, particularly rail transport.

Brake pads on wheel-mounted disc brakes are often used in rail transport due to their good thermal properties and robustness. During braking, both the disc and the pads are worn. This wear process generates particles that may become airborne and thus affect human health. The long term purpose of ‘Airborne particles in Rail transport’ project is to gain knowledge on the wear mechanisms in order to find means of controlling the number and size distribution of airborne particles. In this regard, a series of full-scale field tests and laboratory tests with a pin-on-disc machine have been conducted. The morphology and the matter of particles, along with their size distribution and concentration, have been studied. The validity of results from the pin-on-disc simulation has been verified by the field test results. Results show an ultra-fine peak for particles with a diameter size around 100 nm in diameter, a dominant fine peak for particles with a size of around 350 nm in diameter, and a coarse peak with a size of 3-7 μm in diameter. Materials such as iron, copper, aluminium, chromium, cobalt, antimony, and zinc have been detected in the nano-sized particles.

Selected papers from 14th Nordic Symposium on Tribology, NORDTRIB 2010. Updated from Submitted to Published.

This is the author’s version of a work that was accepted for publication in Wear. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in WEAR, VOL 273, ISSUE 1, (17 June 2011), DOI: 10.1016/j.wear.2011.04.013.

QC 20111221

No abstract

Inhalable airborne particles have inverse health effects. In railways, mechanical brakes, the wheel-rail contact, current collectors, ballast, sleepers, and masonry structures yield particulate matter. Field tests examined a Swedish track using a train instrumented with particle measurement devices, brake pad temperature sensors, and speed and brake sensors. The main objective of this field test was to study the characteristics of particles generated from disc brakes on a running train with an on-board measuring set-up. Two airborne particle sampling points were designated, one near a pad-rotor disc brake contact and a second under the frame, not near a mechanical brake or the wheel-rail contact; the numbers and size distributions of the particles detected were registered and evaluated under various conditions (e.g. activating/ deactivating electrical brakes or negotiating curves). During braking, three speed/temperaturedependent particle peaks were identified in the fine region, representing particles 280, 350, and 600 nm in diameter. In the coarse region, a peak was discerned for particles 3-6 mm in diameter. Effects of brake pad temperature on particle size distribution were also investigated. Results indicate that the 280-nm peak increased with increasing temperature, and that electrical braking significantly reduced airborne particle numbers. Field emission scanning electron microscope images captured particles sizing down to 50 nm. The inductively coupled plasma mass spectrometry results indicated that Fe, Cu, Zn, Al, Ca, and Mg were the main elements constituting the particles.