Gaurav Trivedi

105 papers A 1B 2C 3Misc 14Journal 43Unranked 40
YearRankTypeTitle / Venue / Authors
2026 Misc conf
Temporal Data Encoding and On-Chip Training of an SNN for ECG Classification.
VLSID
Saras Mani Mishra, Hanumant Singh Shekhawat, Gaurav Trivedi
2025 — conf
Accelerating Equation Solvers using Gauss-Jacobi on Multi-FPGA Systems with Ring NoC.
ISVLSI
Shruti Patkar, Harsh, Souraja Kundu, Gaurav Trivedi
2025 J jnl
FPGA-Based Adaptive LIF Neuron for High-Speed, Energy-Efficient Spiking Neural Network.
IEEE Trans. Circuits Syst. Artif. Intell.
Saras Mani Mishra, Hanumant Singh Shekhawat, Jan Pidanic, Gaurav Trivedi
2025 J jnl
Hardware-Optimized Regression Tree-Based Sigmoid and Tanh Functions for Machine Learning Applications.
IEEE Trans. Circuits Syst. II Express Briefs
Akash Dev Roshan, Prithwijit Guha, Gaurav Trivedi
2024 J jnl
A Low-Power Co-Processor to Predict Ventricular Arrhythmia for Wearable Healthcare Devices.
IEEE Trans. Very Large Scale Integr. Syst.
Meenali Janveja, Rushik Parmar, Srichandan Dash, Jan Pidanic, Gaurav Trivedi
2024 J jnl
An SNN-Inspired Area- and Power-Efficient VLSI Architecture of Myocardial Infarction Classifier for Wearable Devices.
IEEE Trans. Circuits Syst. II Express Briefs
Rushik Parmar, Khushil Yadav, Gauraangi Anand, Gaurav Trivedi
2024 — conf
IoT-Enabled RC4-Stream-Cipher Powered Edge Data Encryption for Smart Home.
ICECET
Praveen Tiwari, Maria Kiran Kocherla, Shyra Nandanapu, Pinakeswar Mahanta, Gaurav Trivedi
2024 J jnl
Low complexity, high throughput, energy efficient, pipelined and reconfigurable ASIC realization architecture for multi-layer perceptron models.
Neurocomputing
Raghuvendra Pratap Tripathi, Virat Krishna, Manish Tiwari, Gaurav Trivedi, Amit Dhawan, Prashant Kumar
2024 — conf
Rapid Prototyping of CRYSTALS-Kyber Primitives on FPGA using Python-only HW-SW Flow.
VDAT
Dhruva S. Hegde, Mandar Datar, Manish Prajapati, Sachin B. Patkar, Gaurav Trivedi
2024 — conf
Reprogrammable Time-Domain RRAM Based Vector Matrix Multiplier for In-Memory Computing.
ISQED
Bipul Boro, Rushik Parmar, Ashvinikumar Dongre, Gaurav Trivedi
2024 J jnl
Towards Leveraging Large Language Models for Automated Medical Q&A Evaluation.
CoRR
Jack Krolik, Herprit Mahal, Feroz Ahmad, Gaurav Trivedi, Bahador Saket
2023 J jnl
A High Frequency MOS-Based Floating Charge-Controlled Memcapacitor Emulator.
IEEE Trans. Circuits Syst. II Express Briefs
Ananda Y. R., Gadipelli Sriharsha Satyanarayan, Gaurav Trivedi
2023 J jnl
A MOS-DTMOS Implementation of Floating Memristor Emulator for High-Frequency Applications.
IEEE Trans. Very Large Scale Integr. Syst.
Ananda Y. R., Nehal Raj, Gaurav Trivedi
2023 — conf
A Novel Dynamic Memristor Window Function for High Frequency Applications.
NEWCAS
Ananda Y. R., Subhashis Das, Gaurav Trivedi
2023 J jnl
A Resource Efficient Software-Hardware Co-Design of Lattice-Based Homomorphic Encryption Scheme on the FPGA.
IEEE Trans. Computers
Bikram Paul, Tarun Kumar Yadav, Balbir Singh, Srinivasan Krishnaswamy, Gaurav Trivedi
2023 J jnl
ADC-Less Reprogrammable RRAM Array Architecture for In-Memory Computing.
IEEE Trans. Very Large Scale Integr. Syst.
Ashvinikumar Dongre, Bipul Boro, Gaurav Trivedi
2023 — conf
An Adaptive Window Function based Memristor Model.
RADIOELEKTRONIKA
Ananda Y. R., Arkadeep Hajra, Gaurav Trivedi
2023 J jnl
An Optimized Low-Power VLSI Architecture for ECG/VCG Data Compression for IoHT Wearable Device Application.
IEEE Trans. Very Large Scale Integr. Syst.
Meenali Janveja, Ashwani Kumar Sharma, Abhyuday Bhardwaj, Jan Pidanic, Gaurav Trivedi
2023 — conf
Binary Synaptic Array for Inference and Training with Built-in RRAM Electroforming Circuit.
ISQED
Ashvinikumar Dongre, Gaurav Trivedi
2023 — conf
Comparison of Hardware Implementations of Cryptographic Algorithms for IoT Applications.
RADIOELEKTRONIKA
Sushree Sila P. Goswami, Gaurav Trivedi
2023 J jnl
Design of DNN-Based Low-Power VLSI Architecture to Classify Atrial Fibrillation for Wearable Devices.
IEEE Trans. Very Large Scale Integr. Syst.
Rushik Parmar, Meenali Janveja, Jan Pidanic, Gaurav Trivedi
2023 J jnl
FPGA Implementation of Modified SNOW 3G Stream Ciphers Using Fast and Resource Efficient Substitution Box.
IEEE Embed. Syst. Lett.
Sushree Sila P. Goswami, Gaurav Trivedi
2023 J jnl
Fast power density aware three-dimensional integrated circuit floorplanning for hard macroblocks using best operator combination genetic algorithm.
Int. J. Circuit Theory Appl.
Naorem Yaipharenba Meitei, Krishna Lal Baishnab, Gaurav Trivedi
2023 — conf
IndiRA: Design and Implementation of a Pipelined RISC-V Processor.
RADIOELEKTRONIKA
Ankita Tiwari, Prithwijit Guha, Gaurav Trivedi, Nitesh Gupta, Navneeth Jayaraj, Jan Pidanic
2023 — conf
Load-Data Imputation and Economic Feasibility Analysis of an Academic Institution.
ICECET
Praveen Tiwari, Shaik Asma, Navadeep Ganesh U, Pinakeswar Mahanta, Gaurav Trivedi
2023 J jnl
MInSC: A VLSI Architecture for Myocardial Infarction Stages Classifier for Wearable Healthcare Applications.
IEEE Trans. Circuits Syst. II Express Briefs
Meenali Janveja, Rushik Parmar, Gaurav Trivedi
2023 J jnl
Multi-objective Hybrid Particle Swarm Optimization and its Application to Analog and RF Circuit Optimization.
Circuits Syst. Signal Process.
Deepak Joshi, Satyabrata Dash, Sushanth Reddy, Rahul Manigilla, Gaurav Trivedi
2023 — conf
Programmable Binary Weighted Time-Domain Vector Matrix Multiplier for In-Memory Computing.
APCCAS
Bipul Boro, Ashvinikumar Dongre, Rushik Parmar, Gaurav Trivedi
2023 J jnl
RRAM-Based Energy Efficient Scalable Integrate and Fire Neuron With Built-In Reset Circuit.
IEEE Trans. Circuits Syst. II Express Briefs
Ashvinikumar Dongre, Gaurav Trivedi
2023 J jnl
Tensor Based Multivariate Polynomial Modulo Multiplier for Cryptographic Applications.
IEEE Trans. Computers
Bikram Paul, Angana Nath, Srinivasan Krishnaswamy, Jan Pidanic, Zdenek Nemec, Gaurav Trivedi
2022 J jnl
A 28-Gbps Radix-16, 512-Point FFT Processor-Based Continuous Streaming OFDM for WiGig.
Circuits Syst. Signal Process.
Sumit Agarwal, Shaik Rafi Ahamed, Anup Kumar Gogoi, Gaurav Trivedi
2022 J jnl
A DNN-Based Low Power ECG Co-Processor Architecture to Classify Cardiac Arrhythmia for Wearable Devices.
IEEE Trans. Circuits Syst. II Express Briefs
Meenali Janveja, Rushik Parmar, Mayank Tantuway, Gaurav Trivedi
2022 J jnl
A Flux Controlled MOS-Based Optimized High Frequency Meminductor Emulator.
IEEE J. Emerg. Sel. Topics Circuits Syst.
Ananda Y. R., Gadipelli Sriharsha Satyanarayan, Gaurav Trivedi
2022 — conf
A Scalable and Adaptive Convolutional Neural Network Accelerator.
RADIOELEKTRONIKA
Jan Pidanic, Arpan Vyas, Rishav Karki, Prateek Vij, Gaurav Trivedi, Zdenek Nemec
2022 — conf
An Area and Power Efficient VLSI Architecture to Detect Obstructive Sleep Apnea for Wearable Devices.
RADIOELEKTRONIKA
Rushik Parmar, Meenali Janveja, Gaurav Trivedi, Jan Pidanic, Zdenek Nemec
2022 — conf
An Energy Efficient and Resource Optimal VLSI Architecture for ECG Feature Extraction for Wearable Healthcare Applications.
RADIOELEKTRONIKA
Meenali Janveja, Rushik Parmar, Gaurav Trivedi, Jan Pidanic, Zdenek Nemec
2022 J jnl
An Optimized MOS-Based High Frequency Charge-Controlled Memcapacitor Emulator.
IEEE J. Emerg. Sel. Topics Circuits Syst.
Ananda Y. R., Gadipelli Sriharsha Satyanarayan, Gaurav Trivedi
2022 J jnl
An area and power efficient VLSI architecture for ECG feature extraction for wearable IoT healthcare applications.
Integr.
Meenali Janveja, Gaurav Trivedi
2022 J jnl
Application of hash function for generation of modulation data in RadCom system.
Digit. Signal Process.
Tomás Krejcí, Tomás Zálabský, Dusan Kopecký, Gaurav Trivedi
2022 — conf
Comparison of Floating-point Representations for the Efficient Implementation of Machine Learning Algorithms.
RADIOELEKTRONIKA
Saras Mani Mishra, Ankita Tiwari, Hanumant Singh Shekhawat, Prithwijit Guha, Gaurav Trivedi, Jan Pidanic, Zdenek Nemec
2022 — conf
Design and Implementation of a Low Power Area Efficient Bfloat16 based CORDIC Processor.
RADIOELEKTRONIKA
Saras Mani Mishra, Hanumant Singh Shekhawat, Gaurav Trivedi, Jan Pidanic, Zdenek Nemec
2022 — conf
Design of a Low Power and Area Efficient Bfloat16 based Generalized Systolic Array for DNN Applications.
RADIOELEKTRONIKA
Ankita Tiwari, Saras Mani Mishra, Prithwijit Guha, Jan Pidanic, Zdenek Nemec, Gaurav Trivedi
2022 J jnl
Triple Pendulum Based Nonlinear Chaos Generator and its Applications in Cryptography.
IEEE Access
Bikram Paul, Souradip Pal, Abhishek Agrawal, Gaurav Trivedi
2021 J jnl
A Low-Complexity Shifting-Based Conflict-Free Memory-Addressing Architecture for Higher-Radix FFT.
IEEE Access
Sumit Agarwal, Shaik Rafi Ahamed, Anup Kumar Gogoi, Gaurav Trivedi
2021 — conf
Design of Low Power VLSI Architecture for Classification of Arrhythmic Beats Using DNN for Wearable Device Applications.
NorCAS
Meenali Janveja, Mayank Tantuway, Ketan Chaudhari, Gaurav Trivedi
2021 J jnl
Introspection Into Reliability Aspects in AlGaN/GaN HEMTs With Gate Geometry Modification.
IEEE Access
Sushanta Bordoloi, Ashok Ray, Gaurav Trivedi
2021 — conf
Machine Learning for VLSI CAD: A Case Study in On-Chip Power Grid Design.
ISVLSI
Sukanta Dey, Sukumar Nandi, Gaurav Trivedi
2021 J jnl
PGOpt: Multi-objective design space exploration framework for large-Scale on-chip power grid design in VLSI SoC using evolutionary computing technique.
Microprocess. Microsystems
Sukanta Dey, Sukumar Nandi, Gaurav Trivedi
2020 J jnl
3D-IC partitioning method based on genetic algorithm.
IET Circuits Devices Syst.
Naorem Yaipharenba Meitei, Krishna Lal Baishnab, Gaurav Trivedi
2020 — conf
Comparative Review of Approximate Multipliers.
RADIOELEKTRONIKA
Sushree Sila P. Goswami, Bikram Paul, Sunil Dutt, Gaurav Trivedi
2020 — conf
Design of Efficient AES Architecture for Secure ECG Signal Transmission for Low-power IoT Applications.
RADIOELEKTRONIKA
Meenali Janveja, Bikram Paul, Gaurav Trivedi, Gonella Vijayakanthi, Astha Agrawal, Jan Pidanic, Zdenek Nemec
2020 — conf
FPGA Implementation of Simplified Spiking Neural Network.
ICECS
Shikhar Gupta, Arpan Vyas, Gaurav Trivedi
2020 J jnl
FPGA Implementation of Simplified Spiking Neural Network.
CoRR
Shikhar Gupta, Arpan Vyas, Gaurav Trivedi
2020 J jnl
Machine Learning Approach for Fast Electromigration Aware Aging Prediction in Incremental Design of Large Scale On-chip Power Grid Network.
ACM Trans. Design Autom. Electr. Syst.
Sukanta Dey, Sukumar Nandi, Gaurav Trivedi
2020 J jnl
Methodology and comparative design of an efficient 4-bit encoder with bubble error corrector for 1-GSPS flash type ADC.
IET Circuits Devices Syst.
Sarfraz Hussain, Rajesh Kumar, Gaurav Trivedi
2020 — ch.
PGRDP: Reliability, Delay, and Power-Aware Area Minimization of Large-Scale VLSI Power Grid Network Using Cooperative Coevolution.
Intelligent Computing Paradigm
Sukanta Dey, Sukumar Nandi, Gaurav Trivedi
2020 A conf
PowerPlanningDL: Reliability-Aware Framework for On-Chip Power Grid Design using Deep Learning.
DATE
Sukanta Dey, Sukumar Nandi, Gaurav Trivedi
2020 J jnl
PowerPlanningDL: Reliability-Aware Framework for On-Chip Power Grid Design using Deep Learning.
CoRR
Sukanta Dey, Sukumar Nandi, Gaurav Trivedi
2020 — conf
Theoretical Study and Optimization of Apodized Fiber Bragg Grating for Single and Quasi-distributed Structural Health Monitoring Applications.
RADIOELEKTRONIKA
Krishna Mohan Dwivedi, Gaurav Trivedi, Sunil K. Khijwania
2019 B conf
A Cooperative Co-evolution based Scalable Framework for Solving Large-Scale Global optimization Problems.
SMC
Ajeyo Dey, Satyabrata Dash, Likhita Tumati, Saumitra Sharma, Nikhil Megharajani, Meenali Janveja, Ismael Rodríguez, Gaurav Trivedi
2019 J jnl
Analysis, Modeling and Optimization of Equal Segment Based Approximate Adders.
IEEE Trans. Computers
Sunil Dutt, Satyabrata Dash, Sukumar Nandi, Gaurav Trivedi
2019 B conf
Convergence Analysis of River Formation Dynamics Algorithm.
SMC
Satyabrata Dash, Gaurav Trivedi
2019 Misc conf
Current Collapse Reduction Technique Using N-Doped Buffer Layer into the Bulk Region of a Gate Injection Transistor.
VLSID
Koushik Bharadwaj, Ashok Ray, Sushanta Bordoloi, Gaurav Trivedi
2019 Misc conf
Design and Implementation of Low-Power High-throughput PRNGs for Security Applications.
VLSID
Bikram Paul, Apratim Khobragade, Soumith Javvaji Sai, Sushree Sila P. Goswami, Sunil Dutt, Gaurav Trivedi
2019 J jnl
Identifying incidental findings from radiology reports of trauma patients: An evaluation of automated feature representation methods.
Int. J. Medical Informatics
Gaurav Trivedi, Charmgil Hong, Esmaeel R. Dadashzadeh, Robert M. Handzel, Harry Hochheiser, Shyam Visweswaran
2019 J jnl
Interactive NLP in Clinical Care: Identifying Incidental Findings in Radiology Reports.
Appl. Clin. Inform.
Gaurav Trivedi, Esmaeel R. Dadashzadeh, Robert M. Handzel, Wendy W. Chapman, Shyam Visweswaran, Harry Hochheiser
2019 Misc conf
RiverOpt: A Multiobjective Optimization Framework Based on Modified River Formation Dynamics Heuristic.
VLSID
Satyabrata Dash, Sukanta Dey, Anish Augustine, Sankar Dhar, Jan Pidanic, Zdenek Nemec, Gaurav Trivedi
2019 — ch.
StormOptimus: A Single Objective Constrained Optimizer Based on Brainstorming Process for VLSI Circuits.
Brain Storm Optimization Algorithms
Satyabrata Dash, Deepak Joshi, Sukanta Dey, Meenali Janveja, Gaurav Trivedi
2018 J jnl
Accuracy enhancement of equal segment based approximate adders.
IET Comput. Digit. Tech.
Sunil Dutt, Sukumar Nandi, Gaurav Trivedi
2018 — conf
An Interactive NLP Tool for Signout Note Preparation.
ICHI
Gaurav Trivedi, Robert M. Handzel, Shyam Visweswaran, Wendy W. Chapman, Harry Hochheiser
2018 J jnl
Analysis and Design of Adders for Approximate Computing.
ACM Trans. Embed. Comput. Syst.
Sunil Dutt, Sukumar Nandi, Gaurav Trivedi
2018 J jnl
Minimizing area of VLSI power distribution networks using river formation dynamics.
J. Syst. Inf. Technol.
Satyabrata Dash, Sukanta Dey, Deepak Joshi, Gaurav Trivedi
2018 J jnl
Multiobjective analog/RF circuit sizing using an improved brain storm optimization algorithm.
Memetic Comput.
Satyabrata Dash, Deepak Joshi, Gaurav Trivedi
2018 J jnl
NLPReViz: an interactive tool for natural language processing on clinical text.
J. Am. Medical Informatics Assoc.
Gaurav Trivedi, Phuong Pham, Wendy W. Chapman, Rebecca Hwa, Janyce Wiebe, Harry Hochheiser
2018 — conf
PGIREM: Reliability-Constrained IR Drop Minimization and Electromigration Assessment of VLSI Power Grid Networks Using Cooperative Coevolution.
ISVLSI
Sukanta Dey, Satyabrata Dash, Sukumar Nandi, Gaurav Trivedi
2018 — conf
Towards Interactive Natural Language Processing in Clinical Care.
ICHI
Gaurav Trivedi
2017 — conf
A Novel Low Power High Speed BEC for 2GHz Sampling Rate Flash ADC in 45nm Technology.
iNIS
Sarfraz Hussain, Rajesh Kumar, Gaurav Trivedi
2017 J jnl
An Interactive Tool for Natural Language Processing on Clinical Text.
CoRR
Gaurav Trivedi, Phuong Pham, Wendy W. Chapman, Rebecca Hwa, Janyce Wiebe, Harry Hochheiser
2017 — conf
Analytical Partitioning: Improvement over FM.
VDAT
Sameer Pawanekar, Gaurav Trivedi
2017 C conf
Approxhash: delay, power and area optimized approximate hash functions for cryptography applications.
SIN
Sunil Dutt, Bikram Paul, Anshu Chauhan, Sukumar Nandi, Gaurav Trivedi
2017 — conf
Basic CMOS Gate Design by Mixed-Mode Analysis of Step-Channel TMDG-MOSFET.
iNIS
Pankaj Kumar, Syed Samsuz Zaman, Manash Pratim Sarma, Ashok Ray, Gaurav Trivedi
2017 — conf
Comparison and Design of Dynamic Comparator in 180nm SCL Technology for Low Power and High Speed Flash ADC.
iNIS
Sarfraz Hussain, Rajesh Kumar, Gaurav Trivedi
2017 — conf
Design and Simulation of SF-FinFET and SD-FinFET and Their Performance in Analog, RF and Digital Applications.
iNIS
Syed Samsuz Zaman, Pankaj Kumar, Manash Pratim Sarma, Ashok Ray, Gaurav Trivedi
2017 — conf
FEM Based Device Simulator for High Voltage Devices.
VDAT
Ashok Ray, Gaurav Kumar, Sushanta Bordoloi, Dheeraj Kumar Sinha, Pratima Agarwal, Gaurav Trivedi
2017 — conf
Fast FPGA Placement Using Analytical Optimization.
VDAT
Sameer Pawanekar, Gaurav Trivedi
2017 Misc conf
Markov Chain Model Using Lévy Flight for VLSI Power Grid Analysis.
VLSID
Sukanta Dey, Satyabrata Dash, Sukumar Nandi, Gaurav Trivedi
2017 Misc conf
Optimization of 2.4 GHz CMOS Low Noise Amplifier Using Hybrid Particle Swarm Optimization with Lévy Flight.
VLSID
Deepak Joshi, Satyabrata Dash, Ayush Malhotra, Pulimi Venkata Sai, Rahul Das, Dikshit Sharma, Gaurav Trivedi
2016 Misc conf
A Novel Capacitorless DRAM Cell Design Using Band-Gap Engineered Junctionless Double-Gate FET.
VLSID
Dheeraj Kumar Sinha, Amitabh Chatterjee, Vishnuram Abhinav, Gaurav Trivedi, Victor Koldyaev
2016 Misc conf
Applying River Formation Dynamics to Analyze VLSI Power Grid Networks.
VLSID
Satyabrata Dash, Krishna Lal Baishnab, Gaurav Trivedi
2016 Misc conf
Exploring Approximate Computing for Yield Improvement via Re-design of Adders for Error-Resilient Applications.
VLSID
Sunil Dutt, Harsh Patel, Sukumar Nandi, Gaurav Trivedi
2015 Misc conf
A High-Performance Energy-Efficient Hybrid Redundant MAC for Error-Resilient Applications.
VLSID
Sunil Dutt, Anshu Chauhan, Rahul Bhadoriya, Sukumar Nandi, Gaurav Trivedi
2015 Misc conf
A Nonlinear Analytical Optimization Method for Standard Cell Placement of VLSI Circuits.
VLSID
Sameer Pawanekar, Gaurav Trivedi, Kalpesh Kapoor
2015 C conf
Applying an Interactive Machine Learning Approach to Statutory Analysis.
JURIX
Jaromír Savelka, Gaurav Trivedi, Kevin D. Ashley
2015 — conf
Clinical Text Analysis Using Interactive Natural Language Processing.
IUI Companion
Gaurav Trivedi
2015 — conf
Net weighing based timing driven standard cell placer.
VDAT
Sameer Pawanekar, Gaurav Trivedi
2015 — conf
Parallel two step random walk algorithm to analyze VLSI power grid networks.
VDAT
Satyabrata Dash, Vivek Bangera, Vinay B. Y. Kumar, Gaurav Trivedi, Sachin B. Patkar
2015 — conf
TSV aware standard cell placement for 3D ICs.
VDAT
Sameer Pawanekar, Gaurav Trivedi
2015 — conf
Variability-aware parametric yield enhancement via post-silicon tuning of hybrid redundant MAC units.
VLSI-DAT
Sunil Dutt, Anshu Chauhan, Sukumar Nandi, Gaurav Trivedi
2013 J jnl
A Security Framework for NoC Using Authenticated Encryption and Session Keys.
Circuits Syst. Signal Process.
Hemangee K. Kapoor, G. Bhoopal Rao, Sharique Arshi, Gaurav Trivedi
2013 — conf
Kapees: A New Tool for Standard Cell Placement.
VDAT
Sameer Pawanekar, Kalpesh Kapoor, Gaurav Trivedi
2012 — conf
Supporting collaboration in Wikipedia between language communities.
ICIC
Ranjitha Gurunath Kulkarni, Gaurav Trivedi, Tushar Suresh, Miaomiao Wen, Zeyu Zheng, Carolyn P. Rosé
2007 Misc conf
Application of DC Analyzer to Combinatorial Optimization Problems.
VLSI Design
Gaurav Trivedi, Sumit Punglia, H. Narayanan
2007 C conf
Application of Fast DC Analysis to Partitioning Hypergraphs.
ISCAS
Gaurav Trivedi, H. Narayanan
2007 Misc conf
Parallelization of DC Analysis through Multiport Decomposition.
VLSI Design
Gaurav Trivedi, Madhav P. Desai, H. Narayanan
2006 Misc conf
Fast DC Analysis and Its Application to Combinatorial Optimization Problems.
VLSI Design
Gaurav Trivedi, Madhav P. Desai, H. Narayanan