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    Real-time RSET prediction across three types of geometries and simulation training dataset: A comparative study of machine learning models
    (Elsevier, 2024-05-24) Uhlík, Ondřej; Okřinová, Petra; Tokarevskikh, Artem; Apeltauer, Tomáš; Apeltauer, Jiří
    Agent-based evacuation models provide useful data of the evacuation process, but they are not primarily designed for use during an emergency. The paper aims to test predicting RSET using a surrogate ML model trained on a simulation dataset with 60 samples. A total of 9 machine learning algorithms were tested on 3 simple geometries: bottleneck, stairway and walkway. A set of 7 spatial features was used to train the surrogate models. The results showed a relatively good ability of Artificial Neural Network to learn in scenarios involving bottlenecks and stairways, with an R2: 0.99 on the testing dataset. In the walkway scenario, all models experienced a significant drop in performance, with Gradient Boost performing the best (R2: 0.92). The paper demonstrated ability to generalize effectively in bottleneck-type tasks with training on a relatively small dataset containing spatial parameters obtainable in real-time from camera systems.
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    Comparison of Unbound Granular Materials’ Resilient Moduli Determined by Cyclic Triaxial Test and Innovative FWD Device
    (MDPI, 2022-06-02) Stehlík, Dušan; Hýzl, Petr; Dašek, Ondřej; Mališ, Luděk; Kaděrka, Robert; Komenda, Radek; Sachr, Jiří; Veselý, Petr; Spies, Karel; Varaus, Michal
    Our study summarizes findings from a long-term monitoring of pavement on selected road sections with lower traffic intensity. The research involved the comparison of resilient moduli as a design parameter of unbound pavement base layers’ unbound granular materials (UGMs), determined in a laboratory by a test device for a cyclical triaxial test and in situ by impact load test using a falling weight deflectometer (FWD). In particular, the resilient moduli determined in the laboratory by a cyclic triaxial test (Mr,CTT) were compared with the real values of resilient moduli measured by FWD (Mr,FWD). A new, unique, and innovative FWD device was used to determine the Mr,FWD of the UGMs. The innovation lay in the dual-axis deflection measurement—measurement performed not just in the axis parallel to the road, but also in the axis in the transversal direction.
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    The Effect of Compaction Degree and Binder Content on Performance Properties of Asphalt Mixtures
    (Vilnius Gediminas Technical University, 2016-09-16) Hýzl, Petr; Dašek, Ondřej; Varaus, Michal; Stehlík, Dušan; Coufalík, Pavel; Dašková, Jaroslava; Coufalíková, Iva; Nekulová, Pavla
    The effect of compaction degree and binder content on performance properties of asphalt mixtures of an asphalt concrete type for wearing and binder courses are described in the paper. Measurements of stiffness modulus by two-point bending test on trapezoidal shaped specimens, fatigue characteristics, and resistance against frost cracking by thermal stress restrained specimen test have been performed on selected asphalt mixtures. The main aim of the experimental part was to determine to what extent the performance properties of the individual mixtures will be affected when decreasing the compaction degree by 3% in comparison to the optimal design, i.e. from 100% to 97% degree of compaction.
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    Verification and validation of a numerical model of fire and smoke development in a railway tunnel
    (Czech Technical University, 2016-01-01) Cábová, Kamila; Apeltauer, Jiří; Wald, František
    The paper describes the verification and validation of a numerical model of the development of fire and smoke in a railway tunnel carried out in the Fire Dynamic Simulator numerical code. To evaluate the correctness of a numerical solution of the model with respect to the mathematical model, the results are compared with a solution executed in the SmartFire numerical code. The influence of mesh size on the gas temperature results in the vicinity of the fire source is studied. The level of agreement between the numerical model and a physical model is validated by comparing the calculated data with data measured during a fire test in the Valik road tunnel in the Czech Republic.
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    Performance Characteristics of the Open-Graded Asphalt Concrete Filled with a Special Cement Grout
    (Vilnius Gediminas Technical University, 2015-12-14) Čiháčková, Pavlína; Hýzl, Petr; Stehlík, Dušan; Dašek, Ondřej; Šernas, Ovidijus; Vaitkus, Audrius
    This paper presents a performance of the open-graded asphalt concrete filled with a special cement grout in the road structures, introduces practical examples of the usage of this technology and defines the main properties. In addition, laboratory design of asphalt mixtures filled with special grout is researched. Finally, the results obtained from various laboratory tests are evaluated. The paper contains the open-graded asphalt concrete filled with a special cement grout mix design procedure and results of stiffness measurement, low temperature properties, permanent deformation and skid resistance. Open-graded asphalt concrete filled with a special cement grout mixture is compared to the commonly used asphalt mixes. The open-graded asphalt concrete filled with a special cement grout showed better results than the commonly used asphalt mixes by the stiffness and resistance to the permanent deformation characteristics but behavior at the low temperatures is slightly problematic.