Assessment of Antenna Mounting Building Structural Strength using Microtremor Analysis

Any satellite tracking ground station requires fully steerable dish shaped antenna for fixed satellite services. Antenna foundations require special consideration, because they transmit dynamic loads to soil and foundation system, in addition to static loads due to self-weight of foundation, antenna and its accessories. Antenna foundations are of ground foundation or roof top i.e on buildings based on Radio Frequency requirements. To install antennas on existing building, the building should have required strength. To assess the building strength, building natural frequency and damping ratios are determined using Microtremor recorded data. For rotating Antennas, the required building frequency should be more than 8 Hz to avoid resonance effect of antenna structure natural frequency with servo frequency. In this study, the data is collected for building located at National Remote Sensing Centre, ISRO, Shadnagar, Hyderabad by mounting sensor at 3 locations of building. The data collected is analyzed using View 2002 software. FFT analysis is carried out to identify predominant natural modes and frequencies of the Building.

Vibration Analysis of the Drivetrain in Dependence on the Type of Gearbox Suspension Bushing

In the vast majority of technical applications, there is a necessity to transmit the torque from drive to driven machine together with the demand to overcome great distance between given devices. One of the solutions of this problem is the use of a cardan shaft. Operations of connecting shaft and drivetrain are accompanied by oscillations negatively influencing the driver comfort. Main subject of this article is the measurement of vibrations on different parts of a heavy truck and its evaluation by FFT analysis. Measurements are performed with two kinds of suspension bushing which are compared with to each other. Based on the previous measuring, influence of cardan shaft length was also investigated. First of all, dependency on the length of the cardan shaft on deflection angles for V arrangement was evaluated by analytical method. The theoretical introduction is followed by research of eigen frequency depending on the length of the cardan shaft. The results obtained by modal analysis in FEM are verified by experimental modal analysis [1].

DDES Numerical Investigations on Coherent Structures in Trailing-Edge Film Cooling Combined With Pressure-Side Film Hole

The pressure-side cutback is used to design the trailing-edge film cooling. Previous studies have demonstrated the strong unsteady film mixing between the mainstream gas and the slot coolant, resulting in rapid deterioration of the film cooling effectiveness on cutback surface. The shedding vortexes formed by the clockwise and counter-clockwise structures induced by the mainstream and slot coolant shear-layer account for the strong blending. The RANS/LES hybrid turbulence model (DDES) has been proved to capture the locally unstable flows well. The flowfields and temperature of the cutback under eight blowing ratios Mslot = 0.3 ∼ 1.2 are simulated. With the increasing of blowing ratios, the counter-clockwise structures induced by the slot coolant shear-layer are strengthened to dominate the shedding vortexes gradually, which is corresponding to three kinds of coherent structures. Under low Mslot = 0.3 ∼ 0.5 dominated by clockwise structures of the mainstream, the effectiveness increases. Under middle Mslot = 0.5∼0.75 dominated by both clockwise structures of the mainstream and counter-clockwise structures of the slot coolant, the effectiveness decreases. Under high Mslot = 0.75∼1.2 dominated by counter-clockwise structures of the slot coolant, the effectiveness increases again. To weaken the blending at cutback, the pressure-side film hole with Mhole = 0.4 is arranged close to the cutback to rebuild the mainstream shear-layer. The weakened mainstream shear-layer and the assistant hitting of the hairpin vortexes from the hole injection can weaken the strength of the shedding vortexes at cutback, contributing to the improvement of the effectiveness on cutback surface under low Mslot = 0.5 and middle Mslot = 0.75. Under high Mslot = 1.0, the less influence of the hole injection on the shedding vortexes dominated by the slot coolant counter-clockwise structures accounts for slight improvement. Finally, FFT analysis is obtained for two configurations.

Designing of Three Level 3 Phase Inverter Using Improved SPWM Modulation for different Loads

Many high voltage applications require three-phase inverters. The major challenge in inverter designing is the mitigation of harmonic distortion (HD) to achieve better inverting performance. Usually, sinusoidal pulse width modulation (SPWM) is widely used to trigger the inverting switches for controlling the total HD performance in the inverter. To provide the option of multiple operating ranges the multilevel inverters are designed for higher voltage operations. This paper contributes in two passes, first, an improved SPWM modulation is generated for designing the three levels inverter. Then in the second pass, the performance of the THD is evaluated under the different load conditions using V-I measurement. THD is present in the system due to the use of switches. Therefore, this paper has evaluated the performance of the proposed improved SPWM based multilevel inverter for analysis. In order to improve the performance, the modulation index of the SPWM block is varied. The performance of the component report is also presented in the short..the output waveform of the line current and the voltage are compared; The FFT analysis is done to evaluate the comparison of THD performance. It is concluded that improving the SPWM performance and the lording conditions may improve the THD performance also.

Simulation and dSPACE Hardware Implementation of Carrier based SVPWM for Open-end Induction motor

This paper deals with the implementation of carrier based Space vector pulse width modulated methods (SVPWM) in conjunction with a three phase open end induction motor(OEIM). Among various PWM methods, now a day’s carrier based PWM methods draws more attention due to their easier digital implementation. The main focus of this paper is effortless digital implementation of PWM methods to drive the open end induction motor which is supplied using two dc to ac converters (VSI), using various carrier-based Space vector PWM schemes. MATLAB Simulink platform is used to simulate different carrier based PWM methods for the VSI fed Induction motor. In the present work dSPACE 1104 is used for the digital implementation. The simulation and hardware results which are obtained from various modulation techniques for the proposed model are secure produced by using voltage and current waveforms, FFT analysis, and the most predominantly the THD is slighter. Theoretical and realistic values are corroborating by simulation and experimentation.

Instabilities of a freely moving spherical particle in a Newtonian fluid: Direct Numerical Simulation

Direct Numerical Simulations (DNS) were carried out for a freely falling/rising rigid particle in an otherwise quiescent fluid, using a non-Lagrangian multiplier based fictitious domain (FD) method. Validation studies showed that the proposed FD based DNS are in good agreement with the existing experimental results in the transition regime of falling/rising spheres. Simulations done in the transitional regime (50 < Reynolds number (Re) < 1800 and solid-to-fluid density ratios Γ = ρ p / ρ f ${\Gamma}={\rho }_{p}/{\rho }_{f}$ from 0.08 to 4), confirmed that (i) a falling spherical particle (Γ = 4) exhibits a helical trajectory in the range 270 < Re < 320, and (ii) a rising particle (Γ = 0.5) shows a zig-zagging trajectory in the same range of Re. This finding closes the uncertainty to the question as to whether or not rising/falling particles exhibit a helical and a zig-zagging trajectory. In addition to this, a total of seven distinctive flow regimes were identified, which are as follows: (I) vertical straight path (II) steady oblique path (III) Wavy oblique path (IV) zig-zagging path (for 0.08 < Γ < 1) (V) helical path (for 1 < Γ < 4) (VI) early transition to chaos and (VII) chaotic regime. Regime IV occurs only for light particles (Γ < 1), whereas Regime V occurs only for heavy particles (Γ > 1). Fast Fourier Transform (FFT) analysis characterized the presence of a bimodal frequency similar to that exhibited by flow past an isolated stationary bluff body.

Road to chaos in a Duffing oscillator with time delay loop

This article examines a single Duffing oscillator with a time delay loop. The research aims to check the impact of the time delay value on the nature of the solution, in particular the scenario of transition to a chaotic solution. Dynamic tools such as bifurcation diagrams, phase portraits, Poincaré maps, and FFT analysis will be used to evaluate the obtained results.