Towards Model-Based Condition Monitoring of Railway Switches and Crossings

Railway switches and crossings (S&C, turnouts) connect different track sections and create a railway network by allowing for trains to change between tracks. This functionality comes at a cost as the load-inducing rail discontinuities in the switch and crossing panels cause much higher degradation rates for S&C compared to regular plain line track. The high degradation rates create a potential business case for condition monitoring systems that can allow for improved maintenance decisions compared to what can be achieved from periodic inspection intervals using measurement vehicles or visual inspection by engineers in track. \ua0To this end, this thesis addresses the development of tailored processing tools for the analysis of measured data from accelerometers mounted adjacent to the crossing transition in crossing panels. With the presented tools, a condition monitoring framework is established. The analysis procedures showed robustness in processing large datasets. The framework includes the extraction of different crossing panel condition indicators for which the interpretation is supported by multi-body simulations (MBS) of dynamic train–track interaction. Additionally, a demonstrator is presented for MBS model calibration to the measured track responses.A particularly important signal processing tool is the development of a novel sleeper displacement reconstruction method based on frequency-domain integration. Using the reconstructed displacements, the track response is separated into quasi-static and dynamic domains based on deformation wavelength regions. This separation is shown to be a promising strategy for independent observations of the ballast condition and the crossing rail geometry condition from a single measurement source. In addition to sleeper acceleration measurements, field measurements have been performed in which crossing rail geometries were scanned. The scanned geometries have been implemented into a MBS software with a structural representation of the crossing panel, where analyses have been performed to relate the concurrently measured accelerations and crossing rail geometries. To address the variation in operational conditions in the MBS environment, a sample of measured wheel profiles was accounted for in the analysis. This MBS study showed that there is a strong correlation between the crossing rail geometry condition, wheel–rail contact force, and crossing condition indicators computed from the dynamic track responses. Contrasting measured and simulated track responses from the six investigated crossing panels showed a good agreement. This observation supports the validity of the simulation-based condition assessment of crossing rail geometry. Based on the work in this thesis, a foundation is set for developing methods for automatic calibration of S&C MBS models and subsequent damage evolution modelling based on operational online condition monitoring data. This development aims to address S&C service life in a digital environment and presents a key component for building a Digital Twin prototype for S&C condition monitoring

POSSIBILITIES OF APPLYING BIOMASS FOR THE PURPOSES OF ENERGY PRODUCTION AND ENVIRONMENTAL PROTECTION

The aim of the paper is to raise, direct and encourage awareness of the importance of biomass in energy production, as well as to present various possibilities of its use. Increasing demands for energy and growing environmental issues impose the need for energy production from renewable resources. Fossil fuel reserves are finite and their deficit is projected for the coming period. Biogas is one of the renewable resources. The said gas consists of a large amount of methane gas produced by fermenting organic substances from biomass, manure or any other biodegradable material in anaerobic conditions. Electricity production from renewable resources on farms needs to meet numerous conditions, such as environmental protection, bio-safety and animal welfare, as well as a series of technical, organisational, construction, manufacturing and economic requirements imposed by this kind of production. The Lazar Company Ltd. from the town of Blace owns a farm with 600 dairy cows, a dairy which processes 60 000 litres of milk per day, as well as an energy production plant based on biogas, with the capacity of 1mW/hour. In addition, special attention is paid to organic farming, where biomass is said to have multiple applications in energy production in the context of a long-term development trends of certain industries

The Thermal Behaviour of a Cylindrical Air Layer Enclosed between Double Fabric Roof Membranes

Objects covered by fabric roof membranes are specific in terms of energy consumption, primarily because of the negligible thickness of the material and its good thermal conduction properties. One of the ways of improving the energy efficiency of these objects is the implementation of a double fabric roof membrane structure with an enclosed non ventilated air layer. This paper analyzes the thermal-insulation behaviour of the air layer enclosed between tensile fabric roof membranes which are used for structural purposes. The compilation of the necessary data was carried out by measuring a real object covered by a double fabric roof membrane, semi-cylindrical in shape. The surface temperatures of each membrane were measured, as were the outside and inside air temperature and the air temperature between the membranes during the summer months. In addition, the solar irradiance during the same period was also measured. The analysis of the measured data took into consideration all the present forms of energy transmittance (convection, conduction and radiation), as well as the shape of the air layer and the thermal-physical specific features of border surfaces. The results of the study indicate that thermal behaviour of a closed semi-cylindrical air layer depends on the real outer conditions in the summer months. A methodological approach to the thermal modelling of these structures has accordingly been proposed

Constant-roll inflation with tachyon field in the holographic braneworld

We study inflation driven by the tachyon field in the holographic braneworld by assuming the second slow-roll parameter $\eta$ is constant. The parameter $\eta$ can be either defined by the tachyon scalar field and the Hubble parameter or by the Hubble parameter only. By assuming a constant $\eta$, we derive and numerically solve a differential equation for the Hubble expansion rate. We calculate numerically the scalar spectral index and the tensor-to-scalar ratio. We confront the results with the observational data and find some constraints on the free model parameters. The swampland conjectures are discussed in the context of the constant-roll inflation, with some accent on the holographic model

Tachyon constant-roll inflation in Randall-Sundrum II cosmology

We study inflation in a model with constant second slow-roll parameter $\eta$. In this case, the Hubble expansion rate equation has analytical solutions describing four possible, nontrivial inflation scenarios. The evolution of the inflaton governed by a tachyon field is studied in the framework of the standard and Randall-Sundrum II cosmology. The attractor behavior of the solution is briefly demonstrated. Finally, the calculated values of the parameters $n_{\rm s}$ and $r$ are compared with observational data