Sirvi Autor "Viba, J." järgi
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Kirje Analysis of non-stationary flow interaction with simple form objects(2019) Tipans, I.; Viba, J.; Irbe, M.; Vutukuru, S.K.The paper is devoted to the analysis of a non-stationary rigid body interaction in a fluid flow. Initially, an approximate method for determining the forces due to fluid interaction with the rigid body is offered. For this purpose, the plane movement of a mechanical system with an infinite DOF (degrees of freedom) is reduced to 5 DOF motion: 3 DOF for the body and 2 DOF for the areas of compression and vacuum in fluid flow. Differential equations of non-stationary motion are formed by the laws of classical mechanics. The use of an approximate method has been quantified by computer modelling. The average difference in results was found to be small (< 5%). The analysis of the fluid (air) interaction is carried out for a rigid body of two simple geometries - flat plate and diamond. The results obtained are used to refine the parameters of the proposed approximate method that is addressed in the present study for fluid interaction with the non-stationary rigid body. Theoretical results obtained in the final section are used in the analysis of the movement of prismatic bodies in order to obtain energy from the fluid flow.Kirje Investigation of dual varying area flapping actuator of a robotic fish with energy recovery(2020) Tipans, I.; Viba, J.; Irbe, M.; Vutukuru, S.K.Autonomous under-water vehicles (AUV) performing a commanded task require to utilize on-board energy sources. At the time when on-board power source runs low during operation, the vehicle (AUV) is forced to abort the mission and to return to a charging station. The present work proposes the technique of an energy recovery from surrounding medium. This effect is studied for dual action actuator movement that obtains energy from fluid. It is realized that a flapping or vibrating actuator can be used for energy extraction phenomenon apart from the non-traditional propulsive technique. In the present work a simple dual flapping actuator that can switch between simple flat plate and perforated plate at extreme end positions (angles) by using an efficient mechatronic mechanism that would help in overcoming viscous forces of the operating medium is extensively studied. The main objective of the present article is to develop a new approach for energy gain and recharge power pack of on-board sources from the surrounding medium and to create a robotic fish that would work autonomously by using unconventional drive along with the possibility of energy restoration by using dual varying area type vibrating actuator. At the time of recharge, the robotic fish would project its tail (actuator) out of water and use surrounding medium (air) to scavenge the energy. All the equations describing the process are formed according to classical laws of mechanics. The mechatronic system is explained and the results obtained are discussed in detail for air as the operating fluid to scavenge energy.Kirje Study of simultaneous collisions in agricultural machinery and technology(Estonian University of Life Sciences, 2025) Sokolova, S.; Beresnevich, V.; Viba, J.; Irbe, M.; Cerpinska, M.The paper discusses the process of solid body collisions involving simultaneous multipoint contact, which often occurs in agricultural machinery and related technologies. An analytical method is being developed to study such multiple-impact events, which can be applied to dynamic analyses of various high-speed production equipment and technological processes. The method is grounded in the fundamental laws of mechanics and limitations of object motion, utilizing an integral approach to determine impact parameters. Key examples illustrate the application of the proposed method to translational motion, and an analytical approach is presented for determining the rebound velocity of an object subjected to simultaneous impacts at multiple points. This approach requires prior knowledge of the pre-collision velocity, momentum restitution coefficients, and local linear elasticity coefficients at the points of contact. It also demonstrates how impact duration and average impact force can be estimated using local stiffness values and the object's mass. In cases involving rotational motion with straight thrust pulses at specified points, the rebound angular velocity is derived as a function of the initial angular velocity and the restitution coefficients. It is noted that the analysis remains applicable regardless of the number of collision points.Kirje Wind power equipment for small farms and households(Estonian University of Life Sciences, 2024) Beresnevich, V.; Cerpinska, M.; Irbe, M.; Viba, J.This article deals with the development of small-sized wind power equipment as a viable solution for decentralized renewable energy production. To improve operational specifications of conventional turbine models with rotating blades, it is proposed to use a new design of wind power plant synthesized on the base of a closed loop conveyor equipped with flatshaped blades. In this design, blades are mounted on a belt with an opportunity to move together with it in one straight line direction. Air flow interaction with flat blade that performs translation motion is studied by computer simulation using a superposition principle. In accordance with this approach, a fast-chaotic motion of air particles (Brownian motion) is separated from the slow-directed air motion, with the given average velocity. Dynamic analysis of flat blade interaction with air flow is performed for the stationary air flow with constant speed and also for non-stationary flows with wind gusts. Optimization of the system parameters is made using the generated power as a criterion. Simulation results confirm the serviceability and efficient operation of the proposed conveyor type wind power equipment. It can be mounted on the roofs of buildings or rooftops of vehicles, also device is befriended to nature and people.