Dynamic displacement estimation using data fusion

The paper describes a Kalman filtering technique for dynamic displacement estimation using accelerometer and laser sensor measurements. Data fusion of measurements from multiple sensors can give the more accurate results because of different advantages of sensors. Since the acceleration and displacement have different sampling rates, the multi-rate Kalman filter is applied. The filter is expanded with the fixed interval smoother to improve reconstruction accuracy of displacements. A modelled signal consisting of two sinus functions and Gaussian distributed noise is used to validate developed state-space model

Bridging Law Application to Fracture of Fiber Concrete Containing Oil Shale Ash

Concrete is a widely used material in various industries, including hazardous waste management. At the same time, its production creates a significant carbon footprint. Therefore, intensive research is being conducted to create more eco-friendly concrete, for example, partially replacing cement with by-products such as oil shale ash (OSA) or improving properties by adding dispersed fibers such as basalt fibers (BFs). The article consists of experimental testing of nine types of concrete and the modeling of crack propagation in bending. The basic trends of crack propagation in samples of concrete with OSA and BFs are simulated using a two-dimensional Finite Element (FE) model considering only material degradation on the opening crack surface and experimental data of three- and four-point bending tests. Crack propagation is modeled using the bridging law approach. A surrogate model for predicting the peak loading as a function of tensile strength and fracture work was created. An examination of the results of the FE model shows that the bilinear and nonlinear bridging law functions best describe the crack growth in the analyzed material. A comparison of experimental and modeled results showed that the length of the composite BF strongly affects the accuracy of the numerical model

Numerical analysis of large telescopes in terms of induced loads and resulting geometrical stability

Comprehensive numerical studies, involving structural and Computational Fluid Dynamics (CFD) analysis, have been carried out at the Engineering Research Institute “Ventspils International Radio Astronomy Center” (VIRAC) of the Ventspils University College to investigate the gravitational and wind load effects on large, ground-based radio telescopes RT-32 performance. Gravitational distortions appear to be the main limiting factor for the reflector performance in everyday operation. Random loads caused by wind gusts (unavoidable at zenith) contribute to the fatigue accumulation.Upprättat; 2013; 20130322 (joffe)</p

Characterization of Wind Loading of the Large Radio Telescope

This paper describes numerical simulations of windloads on the large parabolic reflector antenna RT-32 with a diameter of 32 m and a methodology of how calculated wind pressure can be transferred to beam-based digital model. The wind flow leads to a compressive load on the dish and thus to a deformation of the reflector. These deformations can cause a performance degradation of the input signal, or even loss of the observed or controlled object. The calculations show that the wind induced force is small in comparison with gravitational loads. Studies have been carried out at the Ventspils International Radio Astronomy Centre (VIRAC) to investigate the wind-loading effects on the radio telescope RT-32 structure. The wind loads are calculated with the help of an open sourced Computational Fluid Dynamics toolkit OpenFOAM

Experimental studies of a single flexibly-mounted rod in a triangular rod bundle in cross-flow

Experiments on flow-induced vibrations using a closely-packed triangular rod array with a pitch-todiameter ratio of 1.1 in water cross-flow was carried out at Paul Scherrer Institute. The bundle consists of 21 row of five rods in each one. Single flexibly-mounted test rod (TR) is in the fourth row in an otherwise fixed array. The test rod can freely move in the transverse and in-line direction. Two accelerometer sensors were attached at both ends of the TR to measure the rod response on the fluid flow. The effect of flow rate on the stability of the flexibly-mounted TR has been analysed. During experiments, it reveals a set of conditions and tendencies for the flow-induced vibration in the closely-packed multi-rod system

Experimental studies of a single flexibly-mounted rod in a triangular rod bundle in cross-flow

Experiments on flow-induced vibrations using a closely-packed triangular rod array with a pitch-todiameter ratio of 1.1 in water cross-flow was carried out at Paul Scherrer Institute. The bundle consists of 21 row of five rods in each one. Single flexibly-mounted test rod (TR) is in the fourth row in an otherwise fixed array. The test rod can freely move in the transverse and in-line direction. Two accelerometer sensors were attached at both ends of the TR to measure the rod response on the fluid flow. The effect of flow rate on the stability of the flexibly-mounted TR has been analysed. During experiments, it reveals a set of conditions and tendencies for the flow-induced vibration in the closely-packed multi-rod system

Analysis of Wind Influence to Radio Astronomy Observations at Irbene Radio-telescope Complex

The results of modelling wind-related deformations in an RT-16 radio telescope (located at Irbene, Latvia) mirror system are presented. The Finite Volume method is used for the development of a Computational Fluid Dynamic model of turbulent airflow around the telescope. An open sourced Computational Fluid Dynamic toolkit Open FOAM is used for the solution of Partial Different Equations. Notable model difficulties arise due to the open nature of the air flow leading to unknown far field turbulence parameters. Our future plans are to create a unified, coupled, liquid-solid interaction model for RT-32/RT-16 antennas

Analysis of Wind Influence to Radio Astronomy Observations at Irbene Radio-telescope Complex

The results of modelling wind-related deformations in an RT-16 radio telescope (located at Irbene, Latvia) mirror system are presented. The Finite Volume method is used for the development of a Computational Fluid Dynamic model of turbulent airflow around the telescope. An open sourced Computational Fluid Dynamic toolkit OpenFOAM is used for the solution of Partial Different Equations. Notable model difficulties arise due to the open nature of the air flow leading to unknown far field turbulence parameters. Our future plans are to create a unified, coupled, liquid-solid interaction model for RT-32/RT-16 antennas