Qualification: 
Ph.D, M.Tech, B-Tech
abhisheks@am.amrita.edu

Dr. Abhishek S. completed his PhD in 2018 and joined Amrita WNA as Assistant Professor in December 2018. Before joing WNA he served as a research scholar in ECE department in Amrita Vishwa Vidyapeetham, Ettimadai Campus. His research areas includes compressed sensing, biomedical signal processing, wavelet design etc.

Education

  • 2018: Ph.D. (Biomedical Signal Processing)
    Amrita Vishwa Vidyapeetham
  • 2011: M.E (Applied Electronics)
    Anna University
  • 2006: B.Tech (Applied Electronics and Instrumentation (AEI))
    Kerala University

Professional Appointments

Year

Affiliation

2013 - 2018 PhD Research Scholar, Amrita Vishwa Vidyapeetham 
Thesis Advisor : Dr. S. Veni
January 17, 2011 – July 30, 2012 Asst: Professor, Baselios Mathew II Engineering College
March 15, 2008 – August 30, 2009 Instrumentation Engineer, Ion Exchange Services Ltd
June 1, 2007 – March 3, 2008 Engineer, Automation and Electrical Fields, Rinac India limited

Publications

Publication Type: Journal Article

Year of Publication Title

2019

Abhishek S., Veni, S., and Narayanankutty, K. A., “Biorthogonal wavelet filters for compressed sensing ECG reconstruction”, Biomedical Signal Processing and Control, vol. 47, pp. 183-195, 2019.[Abstract]


This paper elaborates the design details of a new set of bi orthogonal wavelet filters derived from double sided exponential splines. The designed wavelets are applied in compressed sensing (CS) scenario and results were quite promising. CS is a signal acquisition paradigm, which surpasses the traditional limit of Nyquist sampling. Increasing the reconstruction quality with minimum number of samples in CS is always challenging. We have addressed this challenging task of increasing the reconstruction quality within a minimum number of measurements in CS by developing this new set of biorthogonal wavelet filters. Biorthogonal wavelets have several advantages such as linear phase as compared to orthogonal wavelets. This wavelet which we prefer to call as dew1 (double exponential wavelet 1) is applied in CS based ECG reconstruction scenarios and experimented over 21 data records from MIT arrhythmia data base. A total of 950 experiments were conducted in three CS based methodologies for ECG reconstruction and the results were noted. Over all we were able to get nearly 30% improvement in the reconstruction quality. This paper elaborates the design of these bi orthogonal filters and its application in CS based ECG reconstruction scenario. Other than endorsing the results, we also aim to familiarize this newly designed wavelet so it can be further experimented in different domains. © 2018 Elsevier Ltd

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2017

Abhishek S., Veni, S., and Narayanankutty, K. A., “Exponential-splines in compressed sensing ECG reconstruction”, International Journal of Pure and Applied Mathematics, vol. 114, pp. 299-310, 2017.[Abstract]


Use of Splines are not yet investigated for compressed sensing (CS). We tried exponential splines (1E-splines) and double sided exponential splines (2E-splines, proposed here) in compressed sensing scenario for ECG reconstruction and found that both outperform commonly used wavelets based approaches. Using these splines, peak root mean Square deviation (PRD) values were much lower for the same amount of measurements when compared to bi-orthogonal wavelets. The frequency domain representations of these 2E-Splines were also investigated. More »»

2016

Abhishek S., S. Veni, and Narayanankutty, K. A., “Splines in Compressed Sensing”, International Journal on Advanced Science, Engineering and Information Technology, vol. 6, pp. 469–476, 2016.[Abstract]


It is well understood that in any data acquisition system reduction in the amount of data reduces the time and energy, but the major trade-off here is the quality of outcome normally, lesser the amount of data sensed, lower the quality. Compressed Sensing (CS) allows a solution, for sampling below the Nyquist rate. The challenging problem of increasing the reconstruction quality with less number of samples from an unprocessed data set is addressed here by the use of representative coordinate selected from different orders of splines. We have made a detailed comparison with 10 orthogonal and 6 biorthogonal wavelets with two sets of data from MIT Arrhythmia database and our results prove that the Spline coordinates work better than the wavelets. The generation of two new types of splines such as exponential and double exponential are also briefed here .We believe that this is one of the very first attempts made in Compressed Sensing based ECG reconstruction problems using raw data.

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2016

Abhishek S., S. Veni, and Narayanankutty, K. A., “Improving information content in Compressed Sensing by modifying the random re-construction matrices”, Indian Journal of Science and Technology, vol. 9, 2016.[Abstract]


Background/Objectives: Compressed Sensing (CS) is an efficient sensing paradigm which guarantees reasonable reconstruction with less number of samples. We aim to increase the reconstruction quality of signals in CS. Methods/Statistical Analysis: The behavior of random matrices is analyzed and an efficient method for improving the reconstruction quality is developed in CS based ECG reconstruction applications. The method is compared against Biorthogonal wavelet based approaches. Findings: Our analysis reveals that introduction of a modified column vector in the reconstruction matrix, which contains the sum of all columns of random matrix increases the reconstruction quality in CS applications. This idea was applied to different sparsifying domains and the results are very encouraging. We studied the effect of doing this on the singular values and both unitary matrices U and V. The first singular value (σ) shot up making the condition number high, however there was not much change in the other singular values. The matrix U seems to remain random unitary matrix, where as matrix V has one value becoming unity in its rank space. Application/Improvements: Compared to wavelet based approaches the method shows reasonable improvement in Percentage Root Square Deviation (PRD).

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Publication Type: Conference Paper

Year of Publication Title

2015

Abhishek S., S. Veni, and Narayanankutty, K. A., “A trick to improve PRD during compressed sensing ECG reconstruction”, in Second International Conference on Signal Processing and Integrated Networks (SPIN), 2015 2nd International Conference on, Amity University, Noida, 2015.[Abstract]


In the problem of compressed sensing (CS) successful reconstruction can be achieved by maintaining a low mutual coherence between the columns in the vector space. In this work, a way to increase the mutual incoherence is introduced. This is achieved by replacing certain matrix domain of the sparse random matrix, which is used as the measurement matrix with null space bases. For convenience, this can be replaced even by identity matrices. The result shows that there is a substantial improvement in Peak Root mean Square deviation (PRD). Many different alternatives have been tried out and relative PRD were plotted. Thresholding is generally adapted in CS in order to reduce the PRD values. It was found that without using thresholding technique, it is possible to obtain reduction in PRD values. The time algorithmic performance was also analyzed and found to be better.

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2013

R. Gopinath, Nambiar, T. N. P., Abhishek S., Pramodh, S. M., Pushparajan, M., Ramachandran, K. I., Dr. Santhosh Kumar C., and Thirugnanam, R., “Fault injection capable synchronous generator for condition based maintenance”, in 7th International Conference on Intelligent Systems and Control, ISCO 2013, Coimbatore, Tamilnadu, 2013, pp. 60-64.[Abstract]


This paper presents the design specifications of an experimental setup capable of injecting faults in a synchronous generator to develop and test algorithms for condition based maintenance of aerospace applications. A 3 kVA alternator is designed to inject faults in the stator winding and field windings. The system is capable of injecting open and short circuit faults in the stator and rotor windings using a fault injection unit and record current, voltage and vibration signals from the respective sensors, with programming capability. The response of the synchronous generator during normal condition and faulty condition are discussed. The work reported in this paper will help other researchers develop low cost experimental facility to pursue research in machine condition monitoring. © 2013 IEEE.

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