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.

A Virtual Instrument for Harmonic Characterization of Instrument Transformers

Abstract: A virtual instrument that can be used for performance measurements of Instrument Transformers (IT) under harmonic excitation is developed. Experimental results are shown to validate the proposed method.

A Microprocessor Based Measuring Instrument for Rapid Testing of Transformer Core Material

Abstract: Precise knowledge of the characteristics of core material Is essential for the design of electromagnetic devices I Ike dynamos, I nstrument transformers and relays. Conventional measurement of the core characteristics Is a tedious process as it Involves collection of voluminous data and corrections thereto. An instrument using linear compensating networks and exploiting the processing capabilities of the popular microprocessor is developed for the measurement of core characteristics such as specific iron loss and the dynamic B-H curve. The necessary corrections are Incorporated In the software so that the end result can be straightaway used in design.

Embedded System Design for Autonomous Unmanned Surface Vehicles in Laboratory Environment

Abstract: Sea-keeping, maneuvering, and motion tests of surface vehicle/ship model need self-propelled scale model which can perform different maneuvers. The present work describes the design implementation and testing of embedded system of an autonomous system for unmanned surface vehicles (USVs)/ship model in the laboratory environment. This is a first-time national development test in the wave basin has demonstrated full-free running self-controlled model in a disturbance environment. The central unit of the system is an embedded controller, compact reconfigurable input–output (cRIO) which features a field-programmable gate array (FPGA) and a processor running Linux-based real-time operating system. It performs the main propulsion control, rudder control data logging and telemetry. The peripherals are interfaced with main controller through multifunction input–output module. The RS-232 communication is used to interface the MRU sensor with main controller. LabVIEW is used as programming tool to develop a program to control the peripherals connected to the main controller and data acquisition over a wireless link using Wi-Fi. A graphical user interface is developed to send control commands and visualize the 4-degree of motion at base station in real time.

Probe for measurement of air velocity in oscillating flows

Abstract: Measurement of air velocity when flow is oscillating is required in ocean wave energy studies. A special type of self-rectifying air turbine called "Wells turbine", coupled with induction generator is used for converting the air column movement in a wave energy basin to electrical energy. So far no attempts have been made to study the air velocity variations into and out of the turbine at site. Some efforts for measurement of oscillating air column at laboratory using hot-wire anemometer have been reported. A novel probe, comprising miniature pressure transducers, for the measurement of air velocity variations into and out of the turbine, was designed and developed. The probe was first calibrated and tested at the laboratory before shifting to site for actual measurements. An unidirectional oscillating air flow facility was initially setup at the existing air flow laboratory, which has a variable speed blower as the prime mover. Oscillating flow was generated by a butterfly valve, operated through a function generator. Tests at a nominal frequency of 0.1 Hz and flow velocities upto 35 m/s were conducted. Accuracies of the order of /spl plusmn/2% were estimated for the probe.

A novel signal processing method for the measurement of venous refilling time

Abstract: Methods in vogue for the measurement of venous refilling time (VRT), based on the photo-plethysmographic (PPG) principle, employ a feedback compensation technique to remove the influence of the colour of a patient's skin. Hence these methods require a “standardization phase” for every measurement. Based on an appropriate model for the propagation of light through skin and tissue, a novel signal processing method is proposed for the measurement of VRT. The proposed technique renders the measurement of VRT independent of not only the colour of the skin of a patient but also of source intensity and detector sensitivity. Test results obtained from a prototype unit, built under the LabVIEW virtual environment, establish the validity of the model and the proposed signal processing technique.

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.