V. Jagadeesh Kumar

Bio: V. Jagadeesh Kumar is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Signal conditioning & Capacitive sensing. The author has an hindex of 15, co-authored 83 publications receiving 637 citations. Previous affiliations of V. Jagadeesh Kumar include Indian Institutes of Technology.

Time Frequency Analysis Method for the Detection of Winding Deformation in Transformer

Abstract: An approach for the use of Wigner-Ville Distribution (WVD), a time frequency analysis method, for the detection of winding deformation during short circuit test of a transformer is presented. The method is validated through experiments conducted on a specially designed 6.6 kV voltage transformer. The results of time frequency analysis approach using WVD and time scale analysis using Wavelet Transform (WT) are compared to the results obtained with the frequency response analysis method to identify an optimal signal analysis tool possessing improved sensitivity for the detection of winding deformation in transformers during short circuit tests.

Conductivity Measurement Using Non-Contact Potential Electrodes and a Guard Ring

Abstract: This paper presents an improved method for the measurement of the conductivity of a liquid. In the proffered technique, the contact-type potential terminals of a traditional four lead conductivity probe are replaced with non-contacting terminals thus preventing electrode corrosion and contamination affecting the conductivity measurement. An additional guard electrode introduced in the present design ensures that the current through the external/surrounding medium becomes negligible thus reducing the error due to current flow, external to the probe. A self-balancing signal conditioning circuit, specially designed to suit the probe, alleviates the new problems of the modified probe. Simulation results and the results obtained from a prototype built and tested establish the efficacy of the proposed technique. The worst case error was found to be ± 0.78% with the prototype probe.

A floating wiper inductive voltage divider type displacement transducer

Abstract: A novel, floating wiper, inductive voltage divider (IVD) type displacement transducer is presented here. A self balancing signal conditioning circuit, proposed herein, operates on an IVD with a floating wiper and provides an output that is proportional to the displacement (can be linear or angular) of the wiper. The output is made independent of the coupling capacitor that would arise due to the air gap between the inductive element and the floating wiper. Thus the output of the proffered transducer is unaffected by any jitter that may occur and alter the distance between the wiper and the IVD. The workability of the proposed transducer is extensively verified through simulation studies.

Photoplethysmography Revisited: From Contact to Noncontact, From Point to Imaging

Abstract: Photoplethysmography (PPG) is a noninvasive optical technique for detecting microvascular blood volume changes in tissues. Its ease of use, low cost and convenience make it an attractive area of research in the biomedical and clinical communities. Nevertheless, its single spot monitoring and the need to apply a PPG sensor directly to the skin limit its practicality in situations such as perfusion mapping and healing assessments or when free movement is required. The introduction of fast digital cameras into clinical imaging monitoring and diagnosis systems, the desire to reduce the physical restrictions, and the possible new insights that might come from perfusion imaging and mapping inspired the evolution of the conventional PPG technology to imaging PPG (IPPG). IPPG is a noncontact method that can detect heart-generated pulse waves by means of peripheral blood perfusion measurements. Since its inception, IPPG has attracted significant public interest and provided opportunities to improve personal healthcare. This study presents an overview of the wide range of IPPG systems currently being introduced along with examples of their application in various physiological assessments. We believe that the widespread acceptance of IPPG is happening, and it will dramatically accelerate the promotion of this healthcare model in the near future.