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CONTACT is a computer program to calculate contact areas for 3D frictional contact problems. The program is maintained by VORtech BV. During the bachelor project, it is investigated if the GPU can be used to gain performance during certain parts of the calculations.

Het versnellen van CONTACT door het implementeren van Fast Fourier Transformaties op de GPU met de CUDA en de cuFFT bibliotheek. Met daarna onderzoek over wat de versnelling van de FFTs kan zijn.

Squats, as a kind of short wavelength rail surface defects, have become one of the main rolling contact fatigue problems in railways worldwide. The purpose of this work is to better understand the squatting phenomenon, contribute to reduction and even prevention of squat occurrence, and thereby reduce the related costs. To such an end, a new modeling approach has been developed in this dissertation, i.e. a three-dimensional finite element (FE) model of the vehicle–track interaction. Both wheel set and rail are simulated as three-dimensional continua. A detailed surface-to-surface contact algorithm is integrated within the FE model in order to solve the frictional rolling contact between the wheel and rail. Different traction/braking efforts are simulated. Detailed modeling of the wheel and rail ensures the consideration of important eigen-modes related to squats, mainly in the high frequency range. Other structures of the vehicle–track system are also modeled to appropriate extents. An estimate of contact stresses with sufficient accuracy is the basis of further dynamic, stress, and fatigue analyses of squats. The FE model has been validated for both normal and tangential contact solutions by comparing it to the widely accepted Hertz theory and Kalker’s CONTACT program. Due to the fact that Hertz theory and CONTACT are only applicable to static contact problems, the steady-state rolling contact between smooth wheels and smooth rails, with the contact occurring in the middle of the rail top, is simulated by the FE model for the purpose of validation. The results show that the FE model is reliable for the solution of frictional rolling contact. On the other hand, the FE model can also take into account actual contact geometry, material non-linearity, and transient effects, which are required for more complicated cases like the wheel–rail rolling contact at a squat. Therefore, the newly developed modeling approach provides a valid and promising tool to solve the problem of rolling contact in the presence of friction. With the validated FE model, the influence of plastic deformation on the solution of frictional wheel–rail rolling contact is further investigated. A bi-linear elasto-plastic material model is employed. It is found that the contact geometry change caused by plastic deformation can significantly modify both the normal and the tangential solutions. When squat type defects are added to the rail top, the calculated dynamic contact forces show a good agreement in wavelength with observed squats in the field. This means that vibrations related to squats are captured by the FE model, proving the applicability of the FE modeling in treating the high frequency dynamics of a system containing rolling contact. Furthermore, based on the simulations and field observations, a growth process of squats from light to mature state has been postulated. This postulation has been validated by track monitoring conducted in the Netherlands. Further analyses of the FE simulations show that squats mainly excite the vehicle–track system at two frequencies. The vibration component with the lower frequency can transfer down to the ballast layer, especially at the support close to the squat. The high frequency vibration component has similar magnitude at several fastenings near the squat and is negligible at the ballast layer. For the investigated rolling speed range between 40 and 140 km/h, both two vibration components increase in magnitude and wavelength with the rolling speed. The vibration component at the higher frequency can be absent when the rolling speed is sufficiently low, e.g. at 40 km/h for the simulated system. By evaluating the stress under rolling contact and comparing it with material strength, it is derived that an initial rail surface defect such as an indentation can only grow into a mature squat when it is over a critical size of 6–8 mm under the typical Dutch railway condition. This critical size has also been verified by monitoring tests. The work of this dissertation formed the basis for a ‘Guideline to Best Practice of Squat Treatment’, written upon invitation by the International Union of Railways.

Contact between neighbours is a logical starting point for making a neighbourhood a pleasant place to live. A scientific research has shown that the area in streets where most contact between neighbours takes place is the hybrid zone. Hybrid zones are the zones between one’s private space (ones house) and the public space (the street); things like gardens, personalized sidewalks etc. This graduation thesis is intended to design to stimulate contact between neighbours in streets without a hybrid zone. This thesis is performed as an addition to a research performed by DE ecotecten on the influence of hybrid zones on communication between neighbours. In order to design something which fits the users’ needs and habits an extensive context analysis is done by using among others, generative techniques, data gathering through crowdsourcing and literature. This context analysis has the purpose to understand everything that has to do with being neighbours, and the experience one has with his street. To find out what the differences could be between different neighbourhoods, and what factors influence its specific contact atmosphere, three different neighbourhoods have been taken as research area in which a total of 20 residents have participated; Blijdorp, Bospolder and Pendrecht. Blijdorp is a mostly “white”, safe and friendly neighbourhood with relatively high educated residents. Bospolder and Pendrecht are both very multicultural neighbourhoods. They are so called “probleem wijken”. Although the last two neighbourhoods seem to be demographically like each other, they differ on architecture. The conclusion that can be drawn from the context analysis is that the best neighbour contact is a modest form of contact. Contact consisting of saying hello, a little chat now and then, and some extra neighbour favours with your direct neighbours. Its main function is to keep up the good atmosphere in the street. Saying “hello” actually means “I want to have it nice here”. Saying “hello” is showing your good intentions. It turned out that we all wish for a street with such good modest contact. In Blijdorp they can imagine this dream street with their current neighbours but one of the problems is that they are busy people, not able to spend much time on the street and so not meeting each other often. This in contrary with Bospolder and Pendrecht, where most people cannot imagine this dream street with their current neighbours. The contact atmosphere in these last two neighbourhoods is one of avoiding each other to avoid contact. It seems plausible that the different neighbourhoods will need a different type of design to solve the problems. The causes of lack of contact in Blijdorp are partly created by the lack of a good hybrid zone. In Bospolder and Pendrecht the reasons for lacking contact are to a big extant attributable to the attitude of the people and only to a small extent to the absence of a hybrid zone. To keep within the scope of the research of DE ecotecten it was decided to design for the neighbourhood Blijdorp in this thesis. The design goal to design for Blijdorp is: to offer opportunities to show your good intentions for the street on own initiative. These opportunities are lacking nowadays because the people in Blijdorp don’t have enough opportunities to greet each other, and because of many upstairs houses, not many people can make a façade yard and show their good intentions in that way. In order to reach the goal an interaction vision was made which resulted in three concepts. A. Streetboxes: all neighbours in one street have the key to a shared showcase. It can be used to give, show, inform, ask etc. B. Street shares: Neighbours can buy a piece of a new product for the street, designed by one of the neighbours, and get their name printed on it. C. Save for a tile: One can save for a customizable street tile at the local shops. After an evaluation with a focus group it is decided to explorer the Streetbox concept further: A multifunctional concept which offers opportunities for individual actions on a collective concern without feeling patronized. Through testing the basic interactions in a real street with real residents it turned out the concept was very much liked, and people would find enough purposes to use it, but they felt a bit uncomfortable acting around the Street box. The associations one has with the concept are very important and should be one of “being proud and independent”. To keep the design realistic for possible future realization of the concept it was chosen to keep it simple and basic. Something which is almost innovative in these digital times, but very natural for contact with neighbours who are after all very close by. The final design is called de Straathoek . De Straathoek is a “corner” situated at a central place in the street. It can be used for all kinds of surprising and convenient matters between neighbours; to give, to share, to ask, to discover and to take what is given by somebody else. De Straathoek can only be used by the residents of the accompanying street. Only they will have the knowledge about the combination of the locks. Everyone who puts something in- or takes something out of the Straathoek, can write a note and/or leave a message on the website; the Straathoek online. De Straathoek contains 4 metal showcase boxes. The showcase boxes are attached to an old construction pile. They each contain a solar cell to power a light which will turn on at night in order to get the real showcase feeling. Besides the Straathoek being an object that offers opportunities to show your good intentions for the street, it also creates little connections between neighbours, and it could function as a meeting place in the street. The 10 days final test of the Straathoek with a mock up model and a website in the Sonmansstraat in Blijdorp was mostly a success and made a lot of people enthusiastic, though some recommendations for future design will be made with regards to the website and some other practical adjustments. Because of so many enthusiastic responses from people who believe a real version will soon be placed in their street, it was decided to try and make it a reality. However, it is not a design anybody can make any money with and the municipality doesn’t have enough subsidies to cover the costs. A solution for this problem could be crowdfunding. The Straathoek is an ideal concept to test the possibilities of crowdfunding for urban issues with. A newly seen phenomenon, which is still in an experimental phase, but might be promising. If enough money is raised and the municipality gives permission, Blijdorp will be the first neighbourhood with a Straathoek in its streets, this summer.

Interfacial tension and contact angles are used for the determination of wettability of reservoirs. This knowledge is important in determining capillary pressure and also relative permeabilities. Representative values for field conditions require the determination of these quantities at high pressure and temperature. The paper at hand gives a short introduction to the pendant drop cell and the acquisition of images. A novel data processing method was developed to obtain more accurate values without the spurious scattering of the obtained contact angles. This data processing technique uses both a full description of the bubble shape and of the substrate surface based on first principals. As model system we use carbon dioxide bubbles on different substrates immersed in CO2-saturated hexadecane at 45oC and pressures ranging between atmospheric and 12 MPa. All issues regarding the accuracy of experimental data and data processing are discussed at length. The main emphasis is on the image processing and the subsequent description of the bubble shape in relation to the substrate surface. The image analysis procedure was validated with computer generated bubble shapes with known contact angles. It was found that the novel method could improve the accuracy of the contact angle determinations significantly.

The contact polytope of a lattice is the convex hull of its shortest vectors. In this paper we classify the facets of the contact polytope of the Leech lattice up to symmetry. There are 1, 197, 362, 269, 604, 214, 277, 200 many facets in 232 orbits.

High-voltage transformers have tap changers to regulate the voltage in the high-voltage network when the load changes. Those tap changers are subject to different degradation mechanisms and need regular maintenance. Various defects, like contact degradation, often remain undetected and the probability of maintenance errors cannot be neglected. Preventive diagnosis of dynamic resistance can be used to determine the contact condition and to check the basic function of the tap changer. This can guarantee that the high-voltage transformer can be put back into operation safely after maintenance. In addition, the information obtained can be used for condition-based maintenance. The research of Jur Erbrink elaborates on the condition assessment of tap changers using dynamic resistance measurements. He describes in his thesis the different ways in which the measurements can be performed and how this influences the measurement results. In particular it was emphasized that the dynamic resistance measurements at a lower the test current are more sensitive for long term aging effects. It is also investigated which defects can be detected and how the results can be interpreted.

High-precision manipulation of small-size objects is an attractive and challenging topic for both industrial production and fundamental scientific research. The capability of monitoring micro-samples during handling is essential to the accuracy and efficiency of a handling system for both liquid and solid samples. When handling liquid samples with small volume, tools (such as drop-on-demand inkjet dispensers and on-chip micro-fluidic channels) are often used to generate droplets or liquid segments. The typical volume ranges from nano-liters to several pico-liters, and an accurate control of the sample volume is critical in many applications. The liquid volume can be derived from the detection of the position of the liquid surface in a fluidic channel. On the other hand, when manipulating micro-scale solid objects, such as micromechanical components or living cells, with mechanical tools, a reliable and efficient handling is highly desired. In this case, the in-situ detection on the solid-solid contact between the samples and the mechanical tools, including the contact force, position and orientation, are essential for successful carrying out the high-precision manipulation. With MEMS technology, the position detection for both liquid surface and solid contact can be achieved in a similar fabrication platform. Current existing inspection tools for micro-manipulation have limited capabilities, in terms of resolution, complexity in assembly, and often rely on external equipments, such as microscopes. Their application in high-performance in-situ monitoring is thus limited. Recently, MEMS technology has been widely used to fabricate different kinds of handling tools to miniaturize the micro-manipulation system, for its small-scale, low cost and better reliability. This gives great opportunities to integrate sensing elements directly into the handling tools during the fabrication. With properly-selected sensing principles and the-state-of-the-arts fabrication technologies, compact manipulation system with integrated sensing capability can be implemented. Apart from the design and fabrication of the MEMS sensors, dedicated readout circuitry is required to achieve a good inspection. With the trend of miniaturization of MEMS devices, the level of the output signal is becoming smaller and smaller, and can often be buried in electrical noise as well as undesired signals introduced by parasitic components. In this thesis, we address the detection principles for liquid surface position and solid contact position, as well as their integration and readout issues, by presenting two MEMS approaches using the capacitive and piezoresistive principle, respectively. The first approach is a capacitive sensor integrated into an inkjet nozzle to monitor the position of the ink meniscus inside the nozzle orifice. The second one is a piezoresistive sensor, which monitors contact positions and forces between solid samples and contact surfaces of micro-manipulation tools. The two types of devices share a similar fabrication platform and readout strategy. The fabrication platform is introduced in chapter 2. A bulk micromachining process, employing both the anisotropic wet etching of silicon and the DRIE process, is chosen as a general platform (semi-SOI) to implement the proposed devices. Chapter 3 develops a readout strategy based on the lock-in principle. By modulating the signal of interest to a high-frequency band, the influence of the flicker noise in the readout circuit, which dominates the noise in the low-frequency band, is eliminated. The strategy also suppresses the influence of parasitic capacitances, which otherwise can be fatal to capacitive detection. A femto-Farad capacitive test structure is designed and fabricated. It has a capacitance of two to three orders lower than the conventional MEMS capacitor sensors (typically at pico-Farad level), allowing an experimental study of the proposed readout method for femto-Farad capacitive sensors. A minimum detectable capacitance variation as low as 1 aF, with a signal bandwidth of 100 Hz, is achieved. A capacitive sensor to monitor the position of the ink meniscus in an inkjet nozzle is presented in chapter 4, as a demonstration of liquid surface position detection. Capacitive sensors are very suitable for liquid level detections with a sub-micron resolution thanks to their low intrinsic noise, flexibility in the arrangement of electrodes and possibility to be embedded on the sidewalls of fluidic channels without influencing the liquid flow. However, to integrate vertical electrodes on the sidewall of liquid channel is a challenging task. An IC-compatible process is developed for this purpose, allowing the integration of multiple electrodes with micron-level accuracy. The capacitance of the fabricated sensor varies from 1.5 fF (empty channel) to 13.1 fF (channel filled with 63 pL of water), and a 60 dB resolution is achieved with a 33 kHz measurement bandwidth. The system has a capacitive sensing resolution of 0.057 aF/Hz1/2, which corresponds to a volumetric resolution of 0.22 fL/Hz1/2 and a liquid surface position resolution of 0.17 nm/Hz1/2 in a vertical channel with a diameter of 40 μm. To investigate the principle and technique for detecting the contact position between a micro-object and the contact surface of a handling tool (such as MEMS micro-grippers), miniaturized piezoresistive MEMS sensors are integrated (chapter 5). Piezoresistive sensors are chosen for their small dimensions and straightforward readout method, which allows multiple sensing elements being integrated in a single device and being monitored at a same moment. The developed sensing principle allows an in-situ monitoring of contact conditions, including contact forces and contact positions. Based on this principle, devices have been implemented to realize different functionalities: 1) an array of five sensing plates detecting the orientation of an object and its force distribution on the plates, and 2) a 2D sensing plate detecting a contact force and its 2D contact position on the plate. The devices are fabricated with the “semi-SOI” platform introduced in chapter 2, and are compatible with existing micro-gripper processes developed in the DIMES lab. A basic sensing cantilever is capable of detecting a vertical contact position on its contact surface. The resolution of position detection is 3 μm under an applied contact force of 1 mN. The resolution of the force detection is 3.6 μN. A sensitivity of 2.8 V/N is obtained with an effective supply voltage of 177 mV across the Wheatstone bridge. Combining five sensing cantilevers into a sensing array, a distribution of contact forces between the object and the five adjacent contact surfaces can be monitored, thus allowing the detection of the shape of the object contact front. At the same time, the five measured vertical contact positions allow an estimation of the object position and orientation. The fabricated 2D sensing plate detects the contact position of an applied contact force in 2D. Taking into account the electrical noise, the theoretical spatial resolution of the plate is 5 μm under a contact force of 1 mN, and the force resolution is 10-20 μN. Although the developed devices are designed to be integrated with silicon MEMS based micro-grippers, the concept behind the devices is suitable for many other applications. The devices presented in this thesis successfully demonstrate two different approaches (capacitive and piezoresistive) for in-situ monitoring liquid and solid micro-samples during handling, based on integrated MEMS sensors. The developed principles and techniques can potentially improve the accuracy and efficiency of micro-handling systems. Further research needs to be carried out to investigate the performance of the fabricated devices in existing handling tools, such as inkjet printheads and micro-grippers. This raises several new challenges for future research, including assembly of the sensors on the handling tools, analysis of the detected information and implementation of closed-loop control systems.

In the mechanical industry there is a need for continuous development towards increasing performance of various types of machinery. Critical components in such machines are exposed to gradually harsher operating environments involving higher cyclic stresses and operating temperatures. Examples of such fatigue-exposed components are gears, camshafts and rolling element bearings in engines and gearboxes. The components in the bearing industry are always subject to the high cycle rolling contact fatigue, which ultimately may lead to the failure. In order to better interpret component failures, to accurately predict fatigue life under harsh operating conditions and to further develop the performance of high-strength steel products, a detailed understanding of the fatigue damage and crack initiation mechanisms (especially around non-metallic inclusions) is required. This thesis offers a significant step forward in the understanding of the role of fatigue damage between non-metallic inclusions and the hardened steel matrix during high-cycle rolling contact fatigue. Rolling contact fatigue has been studied by many researchers in the past. There is a significant knowledge present on this subject and particularly on the microstructural changes and crack initiations around non-metallic inclusions under rolling contact fatigue. There were several attempts to describe the crack initiation and growth under these fatigue conditions, but all models presented to date are based on different oversimplifying assumptions which are in several cases in a direct conflict with experimental observations. In conclusion, it is generally acknowledged that the current understanding of the crack initiation mechanism is essentially empirical and provides little guidance for fatigue researchers, steel and bearing developers and model builders. This thesis is focused on the aspects missing in the current knowledge and provides a comprehensive study on the rolling contact fatigue. A combination of state-of-the-art microscopy techniques was used to reveal the micro and nano scale fundamental studies of the microstructural changes and subsurface crack initiation. This work presents a detailed explanation of the different stages of butterfly formation and growth, including the very early stages of the damage process, at the inclusion/matrix interface using a metal physics perspective. It has been shown that early butterfly formation is the result of a rubbing interaction between the debonded oxide inclusion and the steel matrix. This interaction is the result of shear damage and repeated diffusion bonding/debonding during the stress cycle. Due to continued fatigue exposure, the butterfly crack migrates sidewise from the inclusion/matrix interface out into the steel matrix via gradual material transfer across the early formed butterfly wing and the undamaged matrix. This butterfly initiation stage constitutes the overwhelming portion of the total fatigue life. Only in the very late stage of the fatigue life, few butterflies can reach such a size that a further growth can be described using linear elastic fracture mechanics principles. These findings expand the boundaries of the current knowledge and add new understanding of the microstructural processes occurring during rolling contact fatigue. Quantitative modeling was not the primary focus in the thesis, and the findings are therefore essentially described in the qualitative manner. However these findings must be used by modelers as a basis to develop more quantitative description of the butterfly crack formation and other damage processes based on the mechanisms presented here. This will allow the development of models with higher predictive power.

We report on the fabrication and electrical characterization of field-effect devices based on wire-shaped InP crystals grown from Au catalyst particles by a vapor–liquid–solid process. Our InP wires are n-type doped with diameters in the 40–55-nm range and lengths of several micrometers. After being deposited on an oxidized Si substrate, wires are contacted individually via e-beam fabricated Ti/Al electrodes. We obtain contact resistances as low as ∼ 10 kΩ, with minor temperature dependence. The distance between the electrodes varies between 0.2 and 2 μm. The electron density in the wires is changed with a back gate. Low-temperature transport measurements show Coulomb-blockade behavior with single-electron charging energies of ∼ 1 meV. We also demonstrate energy quantization resulting from the confinement in the wire.

We have investigated the contact resistance of rubrene single-crystal field-effect transistors (FETs) with nickel electrodes by performing scaling experiments on devices with channel length ranging from 200 nm up to 300 μm. We find that the contact resistance can be as low as 100 Ω cm with narrowly spread fluctuations. For comparison, we have also performed scaling experiments on similar gold-contacted devices, and found that the reproducibility of FETs with nickel electrodes is largely superior. These results indicate that nickel is a very promising electrode material for the reproducible fabrication of low resistance contacts in organic FETs.

The authors report a systematic study of the bias-dependent contact resistance in rubrene single-crystal field-effect transistors with Ni, Co, Cu, Au, and Pt electrodes. They show that the reproducibility in the values of contact resistance strongly depends on the metal, ranging from a factor of 2 for Ni to more than three orders of magnitude for Au. Surprisingly, field-effect transistors with Ni, Co, and Cu contacts exhibit an unexpected reproducibility of the bias-dependent differential conductance of the contacts once this has been normalized to the value measured at zero bias. This reproducibility may enable the study of microscopic carrier injection processes into organic semiconductors.

This thesis is about random fluctuations over time (or noise) of electric currents and voltages occuring in small (mesoscopic) electronic devices with typical sizes of micro- to nanometre. Even though the theory presented is of a more general nature, research into such systems has been greatly pushed forward by the prospect of building a quantum computer. There are two important aspects to noise which are addressed in this work. The first can be summarised as detection and refers to the idea, that the fluctuations carry information about the microscopic details (geometric design, scattering, temperature) of transport which causes them. The theoretical problem we investigate is then to relate detector signals to fundamental properties of the sample. Secondly, fluctuations can trigger a variety of processes in the environment. Depending on the system one may wish to enhance or diminish such effects. To achieve this goal we study noise-induced effects and the coupling between noise sources and their environment. The precise way in which these fluctuations occur can be found from the theory of Full Counting Statistics (FCS) which provides a cornerstone for this thesis. In chapter 3 the effect of a weak electromagnetic environment on the Full Counting Statistics of a coherent conductor is investigated. We obtain explicit expressions for the correction to the FCS which are further studied by analytical and numerical means. We also present a reinterpretation of the correction in terms of elementary physical events. The major result in that chapter is a universal relation for Full Counting Statistics which holds at arbitrary voltage, temperature and with no regard to the concrete realization of the contact. For FCS this relation takes the form of detailed balance. In chapter 4 we investigate the detection of finite frequency noise using a quantum tunnelling detector. We focus on a concrete experimental setup consisting of a coherent conductor taking the role of the noise source and a tunnel junction (the detector) which is capacitively coupled to it. We show that the detector rate in a certain parameter range is dominated by a two-photon process and a process involving two interacting electrons in the coherent conductor. We find an explicit analytical expression for the detector signal in terms of system parameters: tunnel coupling, transmissions, environment, voltage over the conductor and coupling parameter. Our results facilitate the detection of many-particle events in the context of quantum transport, particularly electron-electron interactions. The non-Gaussian higher moments of the distribution of current fluctuations in a mesoscopic conductor contain more information than is present in average current and noise. However they are inherently difficult to measure. In order to facilitate such experiments, we propose a completely new way for measuring the Full Counting Statistics in chapter 5. We study threshold detection with a Josephson junction coupled to a mesoscopic conductor. We show that the detailed dependence of the junction's escape rate is sensitive to the distinct FCS of specific conductors (tunnel junction, diffusive, ballistic). We also address issues related to the measurement procedure notably feedback and dispersiveness of the detector. Our theoretical results facilitate a new type of electric noise measurement: direct measurement of the full distribution of transferred charge.

Adhesion, or adhesion coefficient, is given by the ratio of the longitudinal tangential (i.e., braking or traction) force over the normal force at the wheel-rail contact. The tangential force that a braking or tractive railway wheel can exert on a rail is limited by the friction coefficient available between the surfaces in contact for a given normal load. In clean steel-on-steel contacts, the friction coefficient is known to be mostly higher than the adhesion requirements for normal traction and braking operations of existing rolling stock. However, contaminations, such as leaves, grease and water, can easily be present at the wheel-rail contact and reduce the friction level, leading to low adhesion problems. In recent decades, some railways, such as in the Netherlands, the United Kingdom, Sweden and Germany, have particularly been affected in autumn due to the presence of moisture and fallen leaves, among other contaminants. When low adhesion occurs, delays in the train service may be the clearest consequence to the railway commuters. However, many other negative effects may arise, such as damages to wheels and rails, signals passed at danger, station platform overruns and even collisions. Therefore, not only the reliability but also the safety and costs of railway transportation may be compromised. Extreme low adhesion conditions in the Netherlands on October 27, 2002 forced the major train operating company (NS) and the infrastructure manager (ProRail) to stop the services on most of the sections of the network during that day and considerable disruptions continued the days after. In order to mitigate the low adhesion problem, the affected infrastructure managers and train operating companies have taken a variety of countermeasures. However, the problems still persist. This may partly be attributed to insufficient understanding of the problem and its possible countermeasures. The investigations presented in this dissertation, which have been commissioned by ProRail and NS within a research project called AdRem, have aimed at improving this understanding towards an effective solution to the problem. Four existing countermeasures have been investigated in this dissertation, namely friction modifiers, sanding, magnetic track brakes and traction control.