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Vidya M. Nair ¹, A. Sivasubramanian ¹

Affiliations
1 Department of EEE, Amaljyothi College of Engineeing, Kerala, IN

Abstract

This paper presents the design and analysis of a current-driven zero current switched full-bridge converter with reduced voltage overstress on the inverter switches. It contains a snubber circuit formed by a switched capacitor circuit and a resonant inductor, connected in the primary side of the coupling transformer. In this converter, the transformer leakage inductance is used as a part of the resonant circuit. Also, snubber capacitor voltage is adaptively controlled. Thus, less resonant energy is circulated. There is no extra voltage stress on the switches. Design, analysis and simulation of the proposed converter are presented in this paper.

Keywords

DC–DC Conversion, High Voltage Converter, Soft Switching, Zero-Current Switching.

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A. Sivasubramanian ¹, G. Arunkumar ¹

Affiliations
1 Department of Mechanical Engineering, Saveetha School of Engineering, Saveetha University, No.162, Poonamalle High Road, Velappanchavadi, Chennai - 600077, Tamil Nadu, IN

Abstract

Objectives: The paper deals with the study on analysis of Elliptical Crack for Al7075-T651 for three Dimensional Elliptical crack emanating from hole of the plate. Methods/Statistical Analysis: The impact of Crack shape and location with respect to various tensile loads on stress intensity factor is analysed. The crack in two holes of the plate is differentiated into different cases and they are analyzed for stress intensity factor. The crack case is formed with respect to the location of the through and part through crack in the model. Findings: The stress intensity factor of the crack geometry is attained by Ansys and the results are compared with Polynomial equation derived by displacement Extrapolation method. The paper also analyses the stress intensity factor along with parametric angle and Beta function of through elliptical crack model for various loads. Application/Improvements: The Stress Intensity factor value obtained can be used in finding the fatigue behaviour of materials under various loading conditions and improvements can be made by further improvement in the geometry of the plate.

Keywords

Al 7075-T651, Beta Function, Displacement Extrapolation, Elliptical Crack, Fatigue, Stress Intensity Factor.

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S. Mohanalakshmi ¹, A. Sivasubramanian ², A. Swarnalatha ³

Affiliations
1 Anna University, Chennai – 600025, Tamil Nadu, IN
2 School of Electronics Engineering, VIT University, Vandalur, Kelambakkam Road, Chennai – 600127, Tamil Nadu, IN
3 Department of Electronics and Communication Engineering, St. Joseph’s College of Engineering, Old Mamallapuram Road, Semmencherry, Chennai – 600119, Tamil Nadu, IN

Abstract

Objectives: Cardiovascular diseases arise mainly due to arterial stiffening leading to atherosclerosis and arteriosclerosis. Contour analysis of second Derivative Photoplethysmogram (SDPPG) reveals cardiovascular properties. In this paper, a novel SDPPG analysis algorithm is used for the assessment of arterial stiffness. Methods/Statistical Analysis: The proposed algorithm based on re-sampling technique is used for an accurate detection of significant points of interest (a, b and e wave) in SDPPG to evaluate desired parameters for the assessment of arterial stiffness. The parameters identified are PPL (PPG peak latency), PNL (PPG notch latency), PNRA (PPG notch relative amplitude), PTNL (peak to notch latency) and NI (Notch Index) and the correlation between these parameters are studied on the records obtained from the large-scale openly available database PhysioNet. Findings: The performance evaluation of the proposed SDPPG analysis algorithm is better than existing methods in terms of sensitivity and positive predictivity for a, b and e wave detection. Correlation analysis were examined for the PPG signals with low and varying amplitudes, regular and irregular heart rhythms and non-stationary signals that varies from healthy adults to unhealthy and aged patients. The positive linear correlation coefficient 'r' ranges from 0.7 to 0.9 for NI and PNL or PNL and PTNL, representing a significant relationship between them whereas PNL and PPL, NI and PTNL or NI and PPL, present a moderate correlation. However, a negative correlation with r = -0.66 is obtained for PNRA and PTNL. The parameters associated with dicrotic notch NI, PNL and PTNL considerably reflect the stiffness of the arteries, with smaller values of these parameters indicating stiffer arteries. Hence, the notch is the valuable characteristics of the PPG Waveform and plays a significant role in the diagnosis of arterial condition. Also, faithful association between arterial stiffness and Pulse Wave Velocity (PWV) can be acquired from PNRA and PNL, as they represent relative height of notch and position of notch with respect to time respectively, instead of Stiffness index (SI) and Reflection Index (RI) that relates stiffness of arteries. Application/Improvement: Although, the number of PPG records used for performance evaluation was self-effacing, a larger database is required to validate the findings of this study.

Keywords

Arterial Stiffness, Dicrotic Notch Detection, Digital Volume Pulse (DVP), Derivative of the Photoplethysmography Signal (SDPPG), Onsets, Second Systolic Peaks.

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