Acoustic Based Localization of Partial Discharge Inside Oil-Filled Transformers

This paper addresses the localization of Partial Discharge through a 3D Finite Element Method analysis of acoustic wave propagation inside a 3-phase 35kV transformer with the help of COMSOL Multiphysics software. Due to the complexity inside transformers, acoustic waves generated by PDs cannot simply be detected with typical acoustic sensors, especially when PDs happen inside inner windings. These waves are distorted and attenuated along with their propagation. The type, number, and position of sensors are essential factors in PD localization inside a transformer. A new installation arrangement of fiber-optic acoustic sensors inside the transformers is proposed with this information. This array of acoustic sensors has significant effects on PD localization accuracy and has immunity from on-site noise and interference; more importantly, they can be installed after transformer manufacturing. They are reachable if needed to be repaired or replaced. Several numerical studies have been carried out considering different PD source positions, and the Levenberge-Marquardt algorithm is employed for solving localization equations.This work was supported by Qatar National Librar

The Role of Zinc Sulfate in Acute Bronchiolitis in Patients Aged 2 to 23 Months

Objective: Evaluating the effect of zinc sulfate in improving the clinical manifestations of acute bronchiolitis in children younger than 2 years. Methods: This was a double blind pilot trial on 50 patients aged 2 to 23 months at Ghaem and Dr. Sheikh Hospitals in Mashhad from January 2008 to March 2009. Patients were randomly divided into two groups: a case group received oral zinc sulfate and to the control group was given placebo. Findings: Mean age of case group was 168.0±108.6 days and control group 169.2±90.4 days (P=0.98) with male predominance in both groups. At first there was no statistically significant difference between the two groups in reducing the symptoms. But 24 hours after treating, improvement of some important manifestations including tachypnea, subcostal and intercostal retraction, wheezing and cyanosis revealed statistically significant difference in control group in comparison with case group (P=0.04). Conclusion: Zinc sulfate has no benefit in improving clinical manifestations of acute bronchiolitis

Detection and Analysis of Partial Discharges in Oil-Immersed Power Transformers Using Low-Cost Acoustic Sensors

Partial Discharge (PD) is one of the symptoms of an electrical insulation problem, and its permanence can lead to the complete deterioration of the electrical insulation in high-voltage equipment such as power transformers. The acoustic emission (AE) method is a well-known technique used to detect and localize PD activity inside oil-filled transformers. However, the commercially available monitoring systems based on acoustic sensors still have a high cost. This paper analyses the ability of low-cost piezoelectric sensors to identify PDs within oil-filled power transformers. To this end, two types of low-cost piezoelectric sensors were fully investigated using time-domain, frequency-domain, and time-frequency analysis, separately. Thereafter, the effectiveness of these sensors for PD detection and monitoring was studied. A three-phase distribution transformer filled with oil was examined. PDs were produced inside an oil-immersed transformer by applying a high voltage over two copper electrodes, and the AE sensors were coupled to the housing of the transformer. By extracting typical features from the AE signals, the PD signals were differentiated from on-site noise and interference. The AE signals were analyzed using acoustic signal metrics such as peak value, energy criterion, and other statistical parameters. The obtained results indicated that the used low-cost piezoelectric sensors have the capability of PD monitoring within power transformers

Software for Detecting Structural Heterogeneity in Single-Molecule Localization Microscopy Data

This software implements the a-priori knowledge-free unsupervised classification of structurally different particles, employing the Bhattacharya cost function as dissimilarity matrix

Software for Detecting Structural Heterogeneity in Single-Molecule Localization Microscopy Data

This software implements the a-priori knowledge-free unsupervised classification of structurally different particles, employing the Bhattacharya cost function as dissimilarity matrix