Tuesday, January 28. 2020
Structure preserving algorithms for simulation of linearly damped acoustic systems
Vasileios Chatziioannou1
1Department of Music Acoustics, University of Music and Performing Arts Vienna, Austria Received: 22 August 2017 ; Accepted in revised form: 22 January 2020
Abstract: Energy methods for constructing time-stepping algorithms are of increased in- terest in application to nonlinear problems, since numerical stability can be inferred from the conservation of the system energy. Alternatively, symplectic integrators may be constructed that preserve the symplectic form of the system. This methodology has been established for Hamiltonian systems, with numerous applications in engineering problems. In this paper an extension of such methods to non-conservative acoustic systems is presented. Discrete conservation laws, equivalent to that of energy-conserving schemes, are derived for systems with linear damping, incorporating the action of external forces. Furthermore the evolution of the symplectic structure is analysed in the continuous and the discrete case. Existing methods are examined and novel methods are designed using a lumped oscillator as an elemental model. The proposed methodology is extended to the case of distributed systems and exemplified through a case study of a vibrating string bouncing against a rigid obstacle.
c 2019 European Society of Computational Methods in Sciences and Engineering Keywords: Energy conservation, symplectic form, mechanical integrator, linear damping Mathematics Subject Classification: 65M06, 65P10, 65Z05
Monday, December 2. 2019
Radiation-Resistant Robotic Complex: Hardware, Software And Mathematical Concepts
E.M. Chavkin1, A.N. Fomin1, V.V. Prikhodko1, A.A. Sobolev1, A.V.Zhukov1, P.E. Kapustin1, V.E. Kiryukhin1, D.S. Lavygin1, V.V. Levshchanov1, S.V. Pavlov2, V.P. Smirnov2, V.V. Svetukhin3
1S.P. Kapitsa Technological Research Institute of Ulyanovsk State University, Ulyanovsk, Russia, vp@kapitsa.tech 2 Sosny Research and Development Company, Dimitrovgrad, Ulyanovsk region, Russia 3 SMC «Technological Center», Zelenograd, Moscow, Russia.
Received: 12 November 2019; Accepted in revised form: 29 November 2019
Abstract. The results of developing a radiation-hardened robotic complex to work in hot cells at nuclear industry facilities are presented. For each constituting element of the complex – arobotic manipulator, a control device with force feedback, control software – a detailed description is given.Special attention is paid to the mathematical basis of the manual control mode implemented by means of an original 6-DoF joystick.Further development of the control software made it possible to create a training simulator, the software part of which is identical to that used for the robotic arm control. The simulator hardware consists of VR equipment and the 6-DoF joystick.
Keywords: robotic complex, manipulator, control device, force feedback, joystick, control algorithms, mathematical basis, radiation-protected chamber, hot cell, training simulator, virtual reality, VR, control software.
Sunday, July 28. 2019
Numerical Analysis of Bearing Capacity of Soil S. Harabinova, E. Panulinova, E. Kormanikova Institute of Structural Engineering, Faculty of Civil Engineering, Technical University of Kosice, 042 00 Kosice, Slovakia
Received 31 January, 2018; accepted in revised form 23 July, 2019
Abstract: The strength of soil and the bearing capacity are a keys design parameters in designing foundations and other earth structures. Proper interpretation of shear strength parameters and the application to bearing capacity problems are presented and evaluated in this paper. Theory of bearing capacity is developed, on the basis of plastic theory, by changing the shear strength parameters for cohesive soil. In foundation design, the capacity of the foundation to support footing load is given by the soil´s bearing capacity, which is a function of its strength parameters. The maximum pressure, that the soil can support at foundation level without failure depends on the bearing capacity of soil. The bearing capacity of soil in purely cohesive material changes linear with cohesion resistance. However, the bearing capacity changes exponential with the angle of internal friction of soil. By comparing obtained results it was founded, that change the angle of internal friction in cohesive soils have more effect on increasing bearing capacity.
© European Society of Computational Methods in Sciences and Engineering Keywords: bearing capacity, foundation, failure, strength of soil, cohesive soil, numerical analysis Mathematics SubjectClassification: 00A69, 49Mxx
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Friday, July 19. 2019
Evaluation of Turbulence Models for Flow Over a Thermally Loaded Hill
Ivan Kološ1, a), Lenka Lausová1, b) and Vladimíra Michalcová1, c)
1VŠB - Technical University of Ostrava, Faculty of Civil Engineering, L. Podéště 1875/17, 708 33 Ostrava-Poruba, Czech Republic
a)Corresponding author: ivan.kolos@vsb.cz, b)lenka.lausova@vsb.cz, c)vladimira.michalcova@vsb.cz
Abstract. CFD models are widely used for modelling of flow over objects, as they provide very good results of the turbulence characteristics of the flow. The aim of the paper is to analyse suitability of selected numerical models of flow in an unstable temperature-stratified boundary layer over the temperature-loaded object. A numerical analysis has been carried out using four turbulence models: Transition SST κ-ω model, LES model, SAS model and DES model. The velocity and temperature fields of a single temperature loaded hill are evaluated in horizontal profiles at four levels of the hill on both, the windward and leeward sides. © European Society of Computational Methods in Sciences and Engineering
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