Flow Structure Detection with Smoothed Particle Hydrodynamics

We discuss how existing flow structure detection methods can be realised in Smoothed Particle Hydrodynamcs (SPH) simulations. We demonstrate the use of the Delta criterion for the detection of instantaneous Eulerian flow structures. The standard calculation of the velocity gradient tensor (VGT) results too noisy gradient field. We propose a correction method based on the idea of XSPH that yields a much smoother VGT field, enabling significantly more accurate structure detection. We also demonstrate on test cases the process in which the instantaneous Eulerian tools are used to locate Lagrangian coherent flow structures

The biomechanical effect of root amputation and degree of furcation involvement on intracoronally splinted upper molar teeth – An in vitro study

Objectives: The aim of this study was to evaluate the effect of the amount of periodontal support and the presence or absence of root amputation on the fracture resistance of intracoronally splinted maxillary molar teeth.Materials and methods: 48 extracted human upper first molars and 48 s premolars were included in the study. All teeth underwent standard mesio-occluso-distal (MOD) (molars) and standard occluso-distal (OD) (premolars) cavity preparation. After the preparation, all molars were root canal treated, and 48 molar-premolar units were created by intracoronal splinting. The units were randomly divided into 4 groups (Groups A-D, 12 units per group): in Groups C and D, the disto-buccal (DB) roots of the molars were amputated, while in Groups A and B, no root amputation was performed. All units were embedded in methacrylate resin at different levels: in Groups A and C, at 4 mm apically from the cemento-enamel junction (CEJ), while in Groups B and D, at 6 mm apically from the CEJ, mimicking the different stages of furcation involvement. All units were submitted first to dynamic and then to static, load-to-fracture mechanical testing. Fracture resistance values were recorded fracture mode was analysed.Results: During the load-to-facture test, Groups A and B (without root amputation) were characterized by significantly higher fracture resistance values compared to Groups C and D (with root amputation) (p Conclusions: Root amputation has a negative effect on the fracture resistance of intracoronally splinted upper first molar-second premolar units with modeled furcation involvement.</p

The development of fly ash – red mud based geopolymer

Taking into account environmental considerations, such as decreasing CO2 emission and the ecological footprint, the utilisation of secondary raw materials is essential for sustainable development. Fly ash is the product of coal combustion plants that is collected by various air cleaning equipment from flue gas, and red mud is the by-product of the Bayer-process, through which alumina can be produced from bauxite. Geopolymerisation is a process that is suitable for the utilisation of such wastes to produce ceramics, cement, concrete etc. with many advantageous properties. The main objective of the article is to present data on the development and examination of geopolymer made out of deposited fly ash from Tatabánya and red mud from Almásfüzitő. During the experiments, red mud was added to previously optimised fly ash geopolymer in various quantities and compressive strength tests were carried out to determine the optimal fly ash and red mud ratio. However, as the cracking of the specimens could be observed, further tests were carried out on the durability of the geopolymers. The effect of the sealing conditions and RM calcination was investigated, both via visual inspection and with FT-IR analysis at the ages of 3, 7, 14, 28 and 90 days. Based on the results, it could be concluded that the sealing conditions have direct effect on the structural characteristics of fly ash – red mud based geopolymers, but further experiments should be carried out for the identification of the ongoing reactions

TRAFFIC AND INTERLOCKING SIMULATION IN RAILWAY OPERATION: THEORY AND PRACTICAL SOLUTIONS

The society demands high safety level, efficiency and economical operation of the railway traffic. One of the key factors to achieve these aims is the human - the personnel operating and controlling railway traffic as well as the personnel supervising track side and on-board safety equipment, such as signaling and interlocking systems, point machines etc. To ensure the low level of human errors, efficient training programs and supporting tools have to be created. Some of the supporting tools are simulators, simulating the traffic, the interlocking or the on-board man-machine interface for different purposes. In the paper, the way how simulators can be designed as re-configurable ones also the data base serving as basic information storage for simulation will be explained