Showing papers by "V. Jagadeesh Kumar published in 2009"
TL;DR: In this paper, a new topology that uses twin unidirectional turbines (which feature a high efficiency spanning a broad range) is proposed, and it is shown that the power output from such a module considerably exceeds existing optimal configurations including those based on a fixed guide vane impulse turbine or a Well's turbine.
104 citations
05 May 2009
TL;DR: A direct digital converter that provides a digital output, proportional to the measurand being sensed by a single active element resistive sensor is presented and a high level of linearity and accuracy is achieved.
Abstract: A direct digital converter that provides a digital output, proportional to the measurand being sensed by a single active element resistive sensor is presented in this paper. To accomplish this task, the structure and the switching sequence of a conventional dual slope, analog to digital converter (DSADC) is appropriately altered so that the altered DSADC accepts the resistance of the sensor as an integral part and provides a digital output that is linearly proportional to the physical quantity being sensed by the resistive sensor. Since the output of the dual slope resistance to digital converter (DSRDC) is dictated only by the magnitudes of a pair of DC reference voltages, a fixed value resistor and the transformation constant of the sensor, the error in the output is minimal. Hence, a high level of linearity and accuracy is achieved. Simulation studies establish the efficacy of the proposed scheme.
19 citations
05 May 2009
TL;DR: A PC based system for non-invasive, in-vivo measurement of carotid artery compliance is proposed here and the accuracy and resolution has been found to meet the requirements of the application.
Abstract: A PC based system for non-invasive, in-vivo measurement of carotid artery compliance is proposed here. The equipment is a low cost and reliable alternative to the expensive B-mode scanner for vessel wall tracking and stiffness measurement of the artery. The system gives an accurate recording of the distensibility waveform of the carotid artery that could then be used to estimate the various measures of arterial compliance. The system is tested with phantom models of the carotid artery and the accuracy and resolution has been found to meet the requirements of the application. Results obtained from human trials have also been presented to illustrate the capability of the instrument to accurately measure carotid artery compliance.
15 citations
TL;DR: The established limit of detection and quantification of monoethylsulfate in Indinavir sulfate by this method was found to be 24 ng/ml and 74 ng/ML respectively, and the overall percent accuracy (recovery) of samples evaluated at different concentration levels was finding to be 97.1, indicating the sensitivity and accuracy of this optimized ion chromatography method.
8 citations
05 May 2009
TL;DR: In this paper, a dual-slope analog-to-digital converter for differential capacitive sensors is proposed. But, the output is dependent only on, apart from the sensitivity of the sensor, a single DC reference voltage.
Abstract: A novel, simple and high accuracy dual slope direct digital converter suitable for differential capacitive sensors is presented in this work. The proposed technique provides a linear digital output proportional to the parameter being sensed by differential capacitive sensors irrespective of the fact that the sensor could possess either a linear or an inverse characteristic. In the proposed technique, the output is dependent only on, apart from the sensitivity of the sensor, a single DC reference voltage. Thus by employing a precision DC reference voltage, high accuracy is easily achieved. The proposed direct capacitance to digital converter is based on the popular dual-slope analog to digital converter structure and hence possesses all the advantages of the dual-slope technique, namely, high resolution, accuracy and immunity to noise and component parameter variations. A prototype built and tested for a typical differential capacitive sensor with a nominal value of 250 pF gave a worst-case error less than 0.05 %.
7 citations
05 May 2009
TL;DR: A virtual instrument developed for acquiring a series of visual and near infrared images of the affected area and subsequent off-line analysis and presentation of the results for stimulated dermal perfusion and inhibition is described.
Abstract: Determining the extent of dermal perfusion is crucial in assessing the healing of chronic wounds, of the kind encountered in diabetic ulcers and burns. An automated, contact-less, non-invasive means of analyzing the dermal perfusion in selected areas would be useful in this process. Such a technique is presented in this paper. It describes a virtual instrument developed for acquiring a series of visual and near infrared images of the affected area and subsequent off-line analysis and presentation of the results. The virtual instrument has been tested with satisfying results for stimulated dermal perfusion and inhibition.
2 citations
05 May 2009
TL;DR: 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 for the measurement of VRT.
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.
1 citations
05 May 2009
TL;DR: In this paper, the viscoelastic properties of polyacrylamide gel based tissue mimicking phantoms have been measured by subjecting the samples to cyclic loading.
Abstract: Most biological soft tissues exhibit viscous behavior in addition to their well known elastic properties. Polyacrylamide gel based tissue mimicking phantoms have been developed. The viscoelastic properties of these phantoms were measured by subjecting the samples to cyclic loading. Samples prepared with varying concentration of monomer were considered so as to cover the normal and pathological lesions. Results obtained in the measurement are fit to three models - Maxwell, Kelvin-Voigt (KV) and Kelvin-Voigt fractional derivative (KVFD) models, in order to determine the best fitting model. KVFD model is found to be best fitting model for the experimental data obtained.
1 citations
01 Jan 2009
TL;DR: In this article, a virtual instrumentation based scheme is developed for the characterization of magnetic materials, which is derived from the comparison method of testing instrument transformers, and a prototype has been developed by suitably modifying an instrument transformer test set.
Abstract: A virtual instrumentation based scheme is developed for the characterization of magnetic materials. The principle used for measurement is derived from the comparison method of testing instrument transformers. A prototype has been developed by suitably modifying an instrument transformer test set. Characterization of magnetic materials at single frequency and multiple frequencies have been carried out. Typical test results obtained are presented in the paper. The developed instrument substantially reduces the testing time associated with magnetic characterization.