Conference papers (NTIS)
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Item Odhad globální střední kvadratické chyby výšky geoidu vypočítané pomocí integrálních transformací(Vysoké učení technické v Brně, Fakulta stavební, 2024) Belinger, Jiří; Pitoňák, Martin; Trnka, Petr; Novák, Pavel; Šprlák, MichalIntegrální transformace funkcionálů gravitačního pole jsou definovány přes celý prostorový úhel na povrchu koule. Navzdory obrovskému a nespornému pokroku v satelitní gravimetrii a gradiometrii umožňují družicové mise zaměřené na gravitační pole přesné určení tohoto pole s prostorovým rozlišením 100 km, tj. pouze v jeho dlouhovlnné části. Na druhé straně existuje potřeba modelů gravitačního pole s vysokým rozlišením v regionálním, národním nebo kontinentálním měřítku, zejména v určování kvazigeoidu nebo geoidu. Potenciální slabinou pozemních dat je přesnost gravitačního pole v dlouhovlnné délce a omezená dostupnost kvůli několika omezením (např. pouště, jezera a velké řeky, lesy nebo nedostatek dobré vůle mezi sousedními zeměmi ke sdílení citlivých dat). Ideální scénář kombinuje pozemní a satelitní data, která se vzájemně doplňují.V příspěvku budou odvozeny a prezentovány vztahy na odhad globálních středních kvadratických chyb výšky geoidu získaných pomocí integrálních transformací. Pro praktický výpočet bude využita znalost přesnosti měřených terestrických dat a formálních chyb globálních družicových modelů tíhového pole Země.
Item Numerical aspects of imperfect joints modelling(The Korean Society of Mechanical Engineers, 2024) Bulín, Radek; Dyk, Štěpán; Hrabačka, Martin; Smolík, Luboš; Hajžman, MichalImperfect joints and their modelling in the framework of multibody systems dynamics draw the attention of many research groups worldwide. Within the contact-based approach, various joint types (rotational, translational, cylindrical, etc.) can be modelled. The ad hoc contact detection models based on the involved geometries are often used for most joint types, and a lot of effort should also be dedicated to the precise detection of contact initiation time. This brings several problems that should be addressed during the numerical solution of the multibody system dynamics. The main problems and their solutions are summarized in this paper.Item Simulating fluid dynamics in a cascade of oscillating blades using a convolutional neural network(University of West Bohemia, 2024) Bublík, Ondřej; Heidler, Václav; Vimmr, JanThe paper aims to create a computational model for compressible viscous fluid flow in a blade cascade. The model's core is a convolutional neural network that predicts the unsteady flow field between three moving blades. The paper will present a method for extending the neural network model to the entire cascade.Item Time periodic solution of linear vibrating systems with time dependent stiffness using periodic collocation(University of West Bohemia, 2023) Dupal, JanThis paper deals with approach to solution of periodic response of systems having periodic time dependent stiffness. The methodology is prepared for systems with degrees of freedom (DOF) but we restrict to 1 DOF systems in this presentation. The presented approach uses time periodic collocation for discretization of the kernel of integral equation describing motion of the systemItem Examining Vortex-Induced Vibration through Convolutional Neural Networks(University of West Bohemia, Univerzitní 8, 301 00 Plze¬, Czech Republic, IC 49777513, 2023) Bublík, Ondřej; Heidler, Václav; Pecka, Aleš; Vimmr, JanThis paper aims to apply CNNs to fluid-structure interaction (FSI) problems. It is worth noting that most prior research utilizing neural networks for fluid flow prediction assumed stationary boundaries. However, for FSI applications, CNNs must predict flow fields with moving boundaries. To address this challenge, we have designed and trained a CNN specifically tailored to predict unsteady, incompressible fluid flow with moving boundaries.Item Numerical simulation of the adhesive interface(Zapadočeská univerzita v Plzni, 2023) Horák, Lukáš; Krystek, JanIn this work, different discrete interface modeling methods in the finite element method were compared on crack propagation in a double cantilever beam sample. The methods used were the cohesive zone model, extended finite element method, and finite element method. The numerical results were further compared with experiments on a simple double cantilever beam sample bonded using Scoth-Weld epoxy adhesive DP490.Item Experimental moose test(Zapadočeská univerzita v Plzni, 2023) Mokhtar, Abdul Ahad; Hynčík, Luděk; Talimian, AbbasIn the future of transportation, highly autonomous vehicles (HAVs) will be crucial. It is necessary to talk about the passengers' safety and comfort while the HAV chooses a maneuver. That is why we realized a study on assessing passengers’ kinematics during a vehicle maneuver. One female and two males of different anthropometry participated on the study after the ethics committee approval. They sit as passengers on the frontal seat and were instrumented by Qualisys markers to be monitored during the maneuver. Several measurements at the speeds of 30 km/h and 50 km/h were performed. The study analyse and compares the motion capture data as a base for validating an active human body model.Item Vibration attenuation properties of piezoelectric metamaterial plates(Zapadočeská univerzita v Plzni, 2023) Hosseinkhani, Ali; Rohan, EduardIn this study, a heterogeneous piezoelectric 2-D plate is considered. The particular heterogeneity due to periodically distributed soft elastic cylinders anchored in the plate provides the antiresonance property inducing a non-dissipative damping within specific frequency ranges called band gaps, where the standing or propagating waves are suppressed. This paper examines different mechanisms for controlling band gap properties and investigates their influences on band gap characteristics. Finally, the band gaps are utilized for controlling the propagation of vibration waves along the piezoelectric plate in the frequency domain.Item Acoustic streaming in homogenized deformable porous media(Zapadočeská univerzita v Plzni, 2023) Rohan, Eduard; Moravcová, FannyThis paper deals with the acoustic streaming (AS) in periodic poroelastic and rigid media. The fluid-structure interaction problem is imposed in elastic scaffolds. The perturbation with respect to a small parameter proportional to the inverse Strouhal number is applied, which leads to the first and the second order sub-problem enabling to linearize the Navier-Stokes equations governing the barotropic viscous fluid dynamics in deforming scaffolds. Subsequent treatment by the asymptotic homogenization leads to a two scale problem where the macroscopic model provides the vibro-acoustic analysis in the Biot-type medium. It yields the AS source term for the second order problem which attains the form of the Darcy flow. The macroscopic and the local microscopic AS effects are examined for different geometries of the suspension particles (inclusions) and frequency of the incident waves.Item The Role of Absolute Positioning Error in Hand-Eye Calibration and Robotic Guidance Systems: An Analysis(IEEE, 2023) Chaluš, Michal; Vaníček, Ondřej; Liška, JindřichRobotic manipulators deal with serious issues due to their absolute positioning error. This error is usually compensated by an operator in classical robot programming using the teach-and-play method. However, it has a significant effect on accuracy of robotic guidance systems (RGS) that automatically generate process tool trajectory based on the measured data from a sensor. In this paper, we firstly describe the various components of an RGS that affect its overall accuracy. We then introduce a proposed model for the calibration process (MCP) that can be used to analyze the effect of absolute positioning errors on the accuracy of hand-eye calibration, six-point calibration of a process tool and mutual transformation between these tools. Simulations were used to evaluate the proposed MCP model. The results of this analysis are crucial for the practical use of RGS.
Item The IMOCO4.E reference framework for intelligent motion control systems(IEEE, 2023) Čech, Martin; Goubej, MartinIntelligent motion control is integral to modern cyber-physical systems. However, smart integration of intelligent motion control with commercial and industrial systems requires domain expertise, industrial ‘know-how’ of the production processes, and resilient adaptation for the various engineering phases. The challenge is amplified with the adoption of advanced digital twin approaches, big data and artificial intelligence in the various industrial domains. This paper proposes the IMOCO4.E reference framework for the smart integration of intelligent motion control with commercial platforms (e.g. from SMEs) and industrial systems. The IMOCO4.E reference framework brings together the architecture, data management, artificial intelligence and digital twin viewpoints from the industrial users of the large-scale ‘Intelligent Motion Control under Industry4.E’ (IMOCO4.E) consortium. The framework envisions a generic platform for designing, developing, and implementing novice and complex motion-controlled industrial systems. Refinements and instantiations of the framework for the IMOCO4.E industrial cases validate the framework’s applicability for various industrial domains throughout the engineering phases and under different constraints imposed on the industrial cases.Item Analytical Design of a Wide Class of Controllers with Two Tunable Parameters Based on H∞ Specifications(IEEE, 2023) Brabec, Michal; Schlegel, MilošFirst, the paper introduces a specific class of controllers with two tunable parameters called affine controllers, which includes almost all controllers with a fixed structure commonly used in industrial practice, including PI(D) controllers. The main result of this paper presents a new analytical method for the design of the H∞ affine controller based on a description of the boundary of the H∞ region in the parametric plane of the controller. A user-friendly interactive implementation of this method, supporting multiple system models, is available at www.pidlab.com. The use of this tool is also illustrated by an example.Item The Frequency Response Estimation Using Swept-sine Excitation with Observer(IEEE, 2023) Dostálek, Lukáš; Schlegel, MilošThis paper deals with obtaining the frequency characteristics of a linear system. A new approach for nonparametric system identification based on the use of a state reconstructor and a sinusoidal swept excitation signal is proposed.The designed solution provides frequency characteristic estimation with the ability to accurately measure points with specific phase lag. Otherwise, the quality of the estimate depends on the sweeping ratio, which is changed adaptively with respect to the desired accuracy. Another parameter to be adaptively varied is the amplitude of the excitation signal, thereby keeping the experiment in the linear mode in the permissible neighborhood of the operating point.The algorithm in the form of a function block is implemented in the REXYGEN control system from the Czech SME company REX Controls.Item Perfect-matching covers of cubic graphs with colouring defect 3(Masarykova univerzita, 2023) Karabáš, Ján; Máčajová, Edita; Nedela, Roman; Škoviera, MartinThe colouring defect of a cubic graph is the smallest number of edges left uncoveredby any set of three perfect matchings. While 3-edge-colourable graphs havedefect 0, those that cannot be 3-edge-coloured have defect at least 3. We show thatevery bridgeless cubic graph with defect 3 can have its edges covered with at most fiveperfect matchings, which verifies a long-standing conjecture of Berge for this class ofgraphs. Moreover, we determine the extremal graphs.Item Improving Handwritten Cyrillic OCR by Font-based Synthetic Text Generator(Springer, 2023) Gruber, Ivan; Picek, Lukáš; Hlaváč, Miroslav; Neduchal, Petr; Hrúz, MarekIn this paper, we propose a straight-forward and effective Font-based Synthetic Text Generator (FbSTG) to alleviate the need for annotated data required for not just Cyrillic handwritten text recognition. Unlike standard GAN-based methods, the FbSTG does not have to be trained to learn new characters and styles; all it needs is the fonts, the text, and sampled page backgrounds. In order to show the benefits of the newly proposed method, we train and test two different OCR systems (Tesseract, and TrOCR) on the Handwritten Kazakh and Russian dataset (HKR) both with and without synthetic data. Besides, we evaluate both systems' performance on a private NKVD dataset containing historical documents from Ukraine with a high amount of out-of-vocabulary (OoV) words representing an extremely challenging task for current state-of-the-art methods. We decreased the CER and WER significantly by adding the synthetic data with the TrOCR-Base-384 model on both datasets. More precisely, we reduced the relative error in terms of CER / WER on (i) HKR-Test1 with OoV samples by around 20% / 10%, and (ii) NKVD dataset by 24% CER and 8% WER. The FbSTG code is available at: https://github.com/mhlzcu/doc_gen.Item Robust and optimal design of fixed structure controllers in collocated motion systems(IEEE, 2023) Goubej, Martin; Tvrz, Jakub; Kubeš, BřetislavThe paper deals with a methodology for the derivation of PI(D) type fixed structure controllers commonly embedded in motion control loops. A collocated control design problem is formulated, considering two different plant outputs. The goal is to tune the controller parameters to achieve both robustness in stability with respect to a feedback variable and optimal performance with respect to a second penalised output. The proposed method is validated by means of a lift control benchmark problem.Item Maintenance Reduction of Medical Robotic Manipulators through Automatic Data-Driven Updates of Feedforward Control(IEEE, 2023) Helma, Václav; Goubej, Martin; Březina, Pavel; Stoutjesdijk, Henry; Alonso, MarcoThe paper presents a new method for data-driven feedforward compensation of static and quasi-static forces acting on a multi-axis medical robotic manipulator. The proposed approach uses a look-up current calibration table (CCT) and an adaptive algorithm updating the CCT to ensure that the manipulator maintains accurate, fast, and safe performance over time. The key aspect of our control strategy is called data assimilation step, which involves modelling the CCT using an approximating function. We use the NURBS (Non-uniform rational basis spline) technique, which has desirable properties such as high accuracy and flexibility in approximating and even interpolating complex functions. The technique allows the manipulator to compensate for external disturbances such as gravity, friction and gear or cabling resistance. This can improve the precision and reduce the downtime of the manipulator due to periodic feedforward recalibration.Item Diagnostics of Anomaly Steam Turbine Behavior in terms of Remote SHM and Cloud Computing(DEStech Publications, 2023) Liška, Jindřich; Jakl, Jan; Vašíček, VojtěchMonitoring of structural health is the important task in terms of ensuring thereliability of the operated technology. It is important especially in case of the steamturbine operation where the unplanned outage is associated with the high financiallosses.The conventional approach for the evaluation of the normal turbine operation isbased on precise specification of the trigger limits for each of the measured signals madeby the technical expert. The abnormal operation is then determined when one of thesignals is outside of the limits. However, it is a non-trivial task to specify trigger limitsfor all measured signals and sometimes it is even not practicable. The method describedin this paper is based on the automatic detection of anomalies in the turbine behaviorwithout the need to precisely specify the trigger limits manually.The approach is based on two steps. The first is to find the behavior of the turbinethat is related to the normal turbine operation. The signal trigger limits are evaluatedautomatically with probabilistic assessment. The second step is to investigate the actualoperation state using the signal measurements. Then if the actual behavior of the turbineis out of the boundary of the normal turbine operation, the anomaly is detected.The described method was validated using the measurement data acquired inoperation of a steam turbine with a nominal power of hundreds MW. As an example ofthe method application, the paper shows the detection of an anomaly, which wassubsequently identified as a contact between the stator and the rotor turbine part. Thiscontact is potentially dangerous because it can change the structure of the machine.The described method is being integrated into the remote monitoring system that isbased on cloud computing and being developed by the authors of this paper. The remotesensing of the turbine operation is nowadays the key to reduce costs in terms ofmaintaining the installed system and frequent visits of technical personal support tocollect the data. The architecture of the monitoring system itself is described in thepaper. The system is important in terms of providing an early warning in case of anunexpected behavior of the turbine. This provides the maintainability and reliability ofthe operated technology. Nowadays more than 30 operated turbines are part of thismonitoring system worldwide.Item Distributed method for Economic Dispatch Problem with the representation of renewable resources(IEEE, 2023) Kubíček, Karel; Wolf, Jindřich; Helma, VáclavThe need to cover the required load across the power grid as efficiently as possible has led to the development of methods for solving a task known as the Economic DispatchProblem (EDP). As the possible number of agents in the network grew, so did the modularity of the entire network, the dynamic changes in its topology were occurring more and more often. This fact led to the development of decentralized methods. In this paper, a gradient distributed algorithm is introduced where models for solar and wind power plants are used. They are also incorporated into the algorithm. They are utilized for recalculation from weather data, specifically the power of the wind and the power of sunlight, to the provided energy output. Power plants based on renewable sources are hence considered in the representation of the given network topology. The described algorithm is ubsequently validated on two examples.Item Distributed method for Economic Dispatch Problem with a battery system and a variable fuel price(IEEE, 2023) Kubíček, Karel; Wolf, Jindřich; Helma, VáclavThe distribution of the required load across all generators in power networks has given rise to methods solving the Economic Dispatch Problem (EDP). The main goal of themethod is to find such a power distribution that the resulting price per unit of energy is minimal. Due to dynamic changes in the structure of the energy network is there currently a shift away from centralized management towards decentralized methods. In this paper, a gradient-based distributed algorithm is introduced. In proposed framework, models for Battery Energy Storage System (BESS) and variable fuel price are used. The BESS model allows energy to be stored or fed back into the grid, which can affect the final price per unit of energy. Dynamical behaviour of BESS effects final price per energy of generator units. This is equally related to the price of fuel, which can represent a change in the price of energy from the given source - the power plant. The described algorithm is subsequently validated on three examples.
