In the paper we present a novel original finite-element formulation for the dynamic analysis of geometrically exact three-dimensional beams. We focus our studies on implicit time-integration schemes and possible approaches for increasing their robustness and numerical stability. In contrast to standard displacement-rotation based approach we present a spatial and temporal discretization based on velocities and angular velocities. To describe the rotational degrees of freedom quaternions are used which elegantly avoids the singularities present in any the three-component parametrization of rotation. The time-integration scheme and the governing equations of the three-dimensional beam are modified accordingly. In the numerical implementation the Galerkin-type discretization is employed to obtain the finite-element formulation of the problem. The result of our studies is accurate, efficient and robust numerical model. Long term stability of calculations without any additional measures taken is an important characteristic of this approach.
COBISS.SI-ID: 7582305
The paper presents sensitivity analysis of coupled heat and moisture transfer model for timber exposed to fire. The objective of the analysis is to discover the non-influential model parameters and the model simplification accordingly. The SRC method revealed that the least influential parameter is specific permeability of dry timber. Therefore the model was adequately simplified by a more simple description of the energy equation, while preserving the accuracy of the results. Thus, the efficiency of the present coupled heat and moisture transfer model was increased.
COBISS.SI-ID: 7421281
Travel time is considered the most useful travel related information as it is the best indicator of the level of service on the road stretch and is completely understandable to all users. Various technologies for measuring traffic flow parameters provide the optimal background for the implementation of data fusion schemes to gain the maximum accuracy from the combination of the available data. The objective of the data fusion is to gain knowledge of predicted departure based travel time from the two outdated accurate measurements. In this paper a new and simple algorithm is proposed for short-term highway travel time prediction by fusing direct travel time measurements estimated by vehicle reidentification, indirect travel time estimated by the extrapolation of spot speed measurements and additional qualitative data in terms of the level of service. The proposed algorithm has been in operation on the A1 highway in Slovenia for more than two years and has shown robust behaviour in the real world environment. The algorithm is capable of providing short-term travel time prediction in real time with a 9 % better accuracy than the presently used travel time prediction algorithms.
COBISS.SI-ID: 7590497
This paper deals with the heat transfer analysis of the 63-year-old and 60-m-high Moste concrete arch-gravity dam, located in Northwest Slovenia. The analysis was performed after a new sophisticated monitoring system had been established, making it possible to perform continuous measurements of the temperatures of the concrete, water, and dam surroundings, i.e., air temperatures and amount of solar insolation. An equation defining nonlinear and nonstationary heat conduction in the case of a two-dimensional space, for a homogeneous isotropic solid whose thermal conductivity is independent of temperature, was solved numerically by means of the finite-element method, taking into account appropriate boundary conditions. The latter involved the effects of changing conditions in the surroundings (i.e., shading, convection,and solar radiation) during the analyzed period of 15 consecutive clear days in the summer. The results show that the measured and calculated temperatures of the concrete at different locations, and at different depths, were in very good agreement.
COBISS.SI-ID: 2114663
The article presents a possibility of using a non-destructive ultrasonic shear wave reflection technique for monitoring hardening process of bitumen. The technique relies on the use of a new measuring instrument called USWR-4 Hardening meter, which was developed to be applicable directly in situ and has been effectively used for cement-based materials so far. It works on the principle of continuous measurement of change of a shear wave reflection coefficient. Three different types of paving grade and two polymer-modified bitumens were used. Results show that the presented ultrasound technique can effectively track a temperature-dependent hardening process of bitumen.
COBISS.SI-ID: 7360097