Observer Based Controller for Magnetic Levitation System
This paper explains Magnetic Levitation system of a train which comprises of guidance track made with magnets. The main objective is to design a proper controller that can suspend and propelled the train on a guidance track made with magnets. To perform the desired task state space model of Magnetic Levitation system is derived. The response of the system is simulated in MATLAB. The open loop response showed that the derived model is unstable. Observer Based Controller (OBC) is designed to analyze the system in closed loop. The controller showed improved performance for different tracks. Different types of realization techniques (minimal realization, balanced realization, modal realization, observer canonical realization) are compared for minimum fragility in controller implementation. The difference among the different realization controllers has been analyzed in detail for rounding off error or truncation error and an optimal non fragile controller design has been presented. Different disturbances were imposed upon the simulated model. All the results are analyzed in open and closed loops. The closed loop response showed that the vehicle is suspend and propelled on the track and the desired results were achieved successfully.
HVAC Breakdown of R12, R12 – Air Mixtures in Sphere gap Electrodes and Proposed Composite insulating Liquid to Reduce the Amount of Transformer Oil In Transformers
* 1 Engr. Muhammad Junaid, 2 Engr. Mehran Tahir, 3 Engr. Kamal Haider, * 4 Engr. Muhammad Aamir * Department of Electrical Engineering, Sarhad University of Science and Information Technology, Peshawar Pakistan. Authors Email Addresses: nattest@gmail.com, razi_tahir321@yahoo.com,kts911us@yahoo.com,aaamir707@yahoo.com Phone: +923459150634 Abstract-Breakdown behavior of a 10 mm point-sphere gap is investigated for R12, R12 (Dichlorodifluoromethane, CCL2F2), air mixtures for pressures of up to 60psi. It is shown that at high gas pressures, mixtures containing high R12 content can have breakdown voltages higher than the corresponding values in air. Furthermore, these voltages are compared with the SF6. And make a comparison of R12 and SF6 in different scenarios i.e. GWP, cost, dielectric strength. Then Ac voltage breakdown characteristics of various combinations of insulating filler in transformer oil for use in transformers were investigated, with the aim of reducing the amount of oil and thus the cost. Tests were conducted on a sphere–sphere electrode in a horizontal arrangement and a sphere–plane electrode in a vertical arrangement. The Breakdown characteristics were also investigated in a modal in which Nomex paper was inserted between filler and the highvoltage electrode. Based on the experiments, optimum conditions are proposed for the application of transformer oil to transformers. Detailed results of investigations of both gas and composite insulating oil are described and discussed in this paper. Index Term-High Voltage, R12 Gas, SF6 Gas, Insulation, Transformer, Nomex Paper, Glass Beads
High-frequency hearing thresholds: effects of age, occupational ultrasound and noise exposure
AbstractPurpose
It has been suggested that high-frequency audiometry (HFA) could represent a useful preventive measure in exposed workers. The aim was to investigate the effects of age, ultrasound and noise on high-frequency hearing thresholds.MethodsWe tested 24 industrial ultrasound-exposed subjects, 113 industrial noise-exposed subjects and 148 non-exposed subjects. Each subject was tested with both conventional-frequency (0.125–8 kHz) and high-frequency (9–18 kHz) audiometry.ResultsThe hearing threshold at high frequency deteriorated as a function of age, especially in subjects more than 30 years old. The ultrasound-exposed subjects had significantly higher hearing thresholds than the non-exposed ones at the high frequencies, being greatest from 10 to 14 kHz. This hearing loss was already significantly evident in subjects with exposure <5 years and increased with years of exposure and advancing age. The noise exposure group had significantly higher hearing thresholds than the non-exposed group at the conventional frequencies 4 and 6 kHz and at the high frequency of 14 kHz. After stratification for age, there was a significant difference between the two groups at 9–10 and 14–15 kHz only for those under 30 years of age.ConclusionMultivariate analysis indicated that age was the primary predictor, and noise and ultrasound exposure the secondary predictors of hearing thresholds in the high-frequency range. The results suggest that HFA could be useful in the early diagnosis of noise-induced hearing loss in younger groups of workers (under 30 years of age).
