Dr. Bhavani Kumar Yellapragada presently works as Scientist SG at the National Atmospheric Research Laboratory (NARL), a unit of the Indian Space Research Organization (ISRO), India. Dr. Kumar has made significant technical contributions to laser remote sensing instrumentation for environmental research in India. Some of these technologies have been transferred to Indian industries for commercialization. These technologies have been employed to remote-sense atmospheric boundary layer, aerosol, clouds, water vapor, winds, and mesospheric Sodium. His works were recognized by ISRO and conferred with ISRO's prestigious Merit Award in 2017. Dr. Kumar has published 104 publications. He has two IPRs granted with patent status listed under ISRO. Currently, he is listed as an expert member under VIDWAN, an MHRD initiative of the Government of India. Dr Kumar is a recognized Mentor of SRF programme of three national science Academies of India. Under this program he mentored 16 M.Tech students an
EDUCATION
M.Sc, PhD
RESEARCH, TEACHING, or OTHER INTERESTS
Earth and Planetary Sciences, Multidisciplinary, Environmental Science, Atmospheric Science
Study of lidar signals of the atmospheric boundary layer using statistical technique Kamana Mishra, Bhavani Kumar Yellapragada Mathematics and Computer Science, 2024 The rotational turbulence caused by mixing the layers of air, wind shear components, mountain waves, aerosol particles, and other pollutants affects the lowest and densest layer of the earth's surface troposphere. Due to the turbulence, the height of the convective boundary layer (CBLH) changes over the day dramatically. We observe the variation in peak positions of lidar backscatter signals by performing a statistical technique for analyzing the behavior of the convective boundary layer (CBL). After that, to examine the behavior of the whole boundary layer, a distribution method and histogram plots will be used. We provide the statistical method for getting the best fit distribution to show how the result leads to the physical observation of data.
Frequency Sensitive Circuit Design Dipti Ulhas Rupwate, Bhavani Kumar Yellapragada IEEE International Conference on Modeling Simulation and Intelligent Computing Mosicom 2024 Proceedings, 2024 Constant power consumption is a problem in lowpower devices, especially in wearable electronics such as ECG monitors. This issue is targeted in the research article by designing and simulating a frequency-sensitive triggering circuit. The purpose is to make a main circuit operational when an input signal is in a particular frequency band, which is the $0-150 \\mathrm{~Hz}$ band. This is done by designing a low pass filter that enables only signals in the required frequency range while blocking other frequencies at the supply of 3.3 V. The filtered signal is then converted from AC to DC using the rectifier circuit, which gives a steady voltage output. A comparator is used to initiate the main circuit by comparing the generated voltage with a reference voltage. The result is a significant decrease in power consumption as the circuit takes only 23.1 $\\mu \\mathrm{W}$, which is immensely lower than ECG wearable devices having a sleep mode power consumption that ranges up to 3 mW. This is the approach that provides a more efficient solution for the constant monitoring of wearable healthcare devices.
Multi-Year CALIPSO Observations of Ubiquitous Elevated Aerosol Layer in the Free Troposphere Over South Asia: Sources and Formation Mechanism G. Kumar, B. L. Madhavan, L. K. Sahu, Y. B. Kumar, J.‐P. Vernier, H. Liu, B. Zhang, A. K. Pandit, R. K. Manchanda, V. K. Dadhwal, P. R. Sinha Journal of Geophysical Research Atmospheres, 2023 The vertical distribution of aerosols in the lower troposphere is critically important for assessing their impact on Earth's radiation budget and modulation of cloud microphysics. This study analyzed cloud‐free aerosol extinction coefficient (βext), aerosol subtypes, and particulate depolarization ratios obtained from CALIOP (Cloud‐Aerosol Lidar with Orthogonal Polarization) over the six regions of India during 2008–2018. We investigated unprecedented climatology of the physical and optical characteristics of elevated aerosol layers (EALs) along with their source and formation mechanism. The key findings include: (a) EALs over the Indian region were persistent between 4 and 6 km during all seasons, (b) geometrical layer thickness of EALs increased up to 36.7% and 25% from the annual mean during summer and fall seasons, respectively, compared to that of spring and winter, (c) dust and polluted dust accounted for up to 50%–80% from near‐surface to 6 km and up to 80%–90% of the EALs between 4 and 6 km, respectively for all the seasons and regions, (d) we anticipated that locally confined recirculation coupled with stratified stable layer capped within turbulent layers could be a possible mechanism of formation of stratified EALs between 4 and 6 km during winter‐spring‐fall, while in summer, vertical transport of pollutants from the PBL to mid‐troposphere due to enhanced deep convection served as a key formation mechanism of the EALs, (e) the second Modern‐Era Retrospective analysis for Research and Applications Global Modeling Initiative model reasonably simulated the shape and vertical gradient of βext with significant differences in magnitude below 4 km; however, it fails to reproduce EALs for all seasons and regions during the study period.
Investigating Atmospheric and Convective Boundary Layer Heights via Active Optical Sensor Signals and Statistical Techniques Kamana Mishra, Bhavani K. Yellapragada Proceedings of SPIE the International Society for Optical Engineering, 2023 The mixing of air layers, wind shear components, mountain waves, aerosol particles, and other pollutants causes rotational turbulence that affects the lowest and densest layer of the earth’s surface troposphere. This turbulence results in a significant change in the height of the Convective Boundary Layer (CBLH) over a day. To analyze the behavior of the convective boundary layer, a statistical technique is used to observe the variation in peak positions of Light Detection and Ranging (LiDAR) back-scatter signals. Furthermore, a statistical method is provided to obtain the best-fit distribution to demonstrate how the result leads to the physical observation of the data. This method involves selecting a suitable distribution for the dataset and defining the percentile bins to use a specific range of the data. The observed frequencies and expected frequencies are then calculated to formulate the chi-square statistics, which are used to determine the fitness of the distribution. Finally, a histogram with the best-fit distribution curve is plotted to examine whether the formulation of the function is appropriate. This approach provides a comprehensive understanding of the behavior of the entire boundary layer and can be used to inform further analysis and interpretation of the data.
Convective Boundary Layer Height Detection from Active Optical Sensor Signals Kamana Mishra, Bhavani Kumar Yellapragada 2022 Workshop on Recent Advances in Photonics Wrap 2022, 2022 The turbulence caused by vertical and horizontal components of wind shear, the presence of aerosol particles, and other pollutants affects the closest layer to the earth's surface i.e., the troposphere. Due to the turbulence, the height of the convective boundary layer (CBLH) changes over the day dramatically. To observe these changes in-depth, peaks of Lidar backscatter signals will be detected using a statistical technique. After that, a statistical technique to find the best fit distribution will be used to examine the behavior of the whole boundary layer.
Survey on deadlocks in distributed database systems Y. Bhavani, K. Praveen Kumar, K. Dharmateja, P. Pranathi, R. Sowmya Proceedings of the 3rd International Conference on Intelligent Communication Technologies and Virtual Mobile Networks Icicv 2021, 2021 In Distributed Database System (DBS) and multitasking system, the occurrence of deadlocks is one of the most serious problems. If a site request for a resource that is already in the another site which is waiting for another resource then the scenario is called as distributed deadlock. Different distributed environments require a suitable deadlock detection algorithm to detect deadlocks. Different distributed environments needs to maintain their platforms by avoiding deadlocks. To achieve this environment, it is required to fed with optimized deadlock detection and avoidance algorithms. In this article, different deadlock detection algorithms that uses Wait For Graph and resolution algorithms to trace out deadlocks were discussed. An optimization technique is used for resolving deadlock in an efficient manner. A comparison between different deadlock detection algorithms based on different parameters like, delay time, message size, number of messages and whether the algorithm detects false deadlocks or not were performed. Based on the comparisons, a few deadlock detection algorithms were suggested for the distributed environment.
Sensing of precipitation using laser radar Optics Infobase Conference Papers, 2021
Investigation on the performance of Levinson recursion algorithm-based Wiener filter in gluing ground-based lidar signals Natarajan Sangeetha Kalaivasan Optical Engineering, 2019 The ground-based lidar is an active remote sensing instrument to profile the lower atmosphere effectively. In general, a lidar receives an analog signal from a lower altitude, a photon count from a higher altitude, and glues them in order to profile the atmosphere effectively. We propose the Levinson recursion algorithm-based Wiener filter over an original lidar signal to convert an analog signal to virtual count. This count is further glued with photon counting through mean square error method, and the results are compared with the linear regression algorithm. It is found that the proposed algorithm enhances the scaled analog from 152 to 8780 MHz in 355 nm, 131 to 3591 MHz in 387 nm, and 79 to 2956 MHz in 408 nm wavelengths. Furthermore, the improvement in correlation coefficients is found to be 0.9899, 0.9942, and 0.9807 for 355, 387, and 408 nm wavelengths, respectively. The proposed algorithm can be applied to any ground-based lidar system for an accurate profiling of the lower atmospheric compositions.
Raman lidar measurements of aerosol and water vapour distribution in the atmosphere: A novel method of signal processing 38th Asian Conference on Remote Sensing Space Applications Touching Human Lives Acrs 2017, 2017
Aerosol lidar method of remote sensing winds in the atmospheric boundary layer using cross correlation technique International Journal of Applied Engineering Research, 2016
Temperature anomalies associated with sudden stratospheric warming, observed above the tropical site of Gadanki (13.5°N, 79.2°E) with a Rayleigh lidar International Journal of Chemical Sciences, 2016
Application of finite difference technique to Raman lidar signals to derive the altitude profiles of atmospheric aerosol extinction International Journal of Engineering and Technology, 2015
Rayleigh lidar observations of mesospheric inversion layers over gadanki (13.5°N, 79.2°E) and their relationship with gravity wave activity Indian Journal of Radio and Space Physics, 2014
Airborne particles washout: A case study investigated using laser radar International Journal of Engineering and Technology, 2013
LIDAR for atmospheric measurement and probing International Journal of Engineering and Technology, 2013
Detection of long range transport of aerosols with elevated layers over high altitude station in the central Himalayas: A case study on 22 and 24 March 2012 at ARIES, Nainital Indian Journal of Radio and Space Physics, 2013
Micro pulse lidar as a tool for active remote sensing of atmospheric particulate International Journal of Engineering and Technology, 2013
A study of equatorial wave characteristics using rockets, balloons, lidar and radar M.N. Sasi, B.V. Krishna Murthy, Geetha Ramkumar, K. Satheesan, K. Parameswaran, K. Rajeev, S.V. Sunilkumar, Prabha R. Nair, K. Krishna Moorthy, Y. Bhavanikumar, K. Raghunath, A.R. Jain, P.B. Rao, M. Krishnaiah, S.R. Prabhakaran Nayars, K. Revathy, S. Devanarayanan Advances in Space Research, 2003
Altitude profiles of temperature from 4 to 80 km over the tropics from MST radar and lidar K Parameswaran, M.N Sasi, Geetha Ramkumar, Prabha R Nair, V Deepa, B.V.Krishna Murthy, S.R.Prabhakaran Nayar, K Revathy, G Mrudula, K Satheesan, Y Bhavanikumar, V Sivakumar, K Raghunath, T Rajendraprasad, M Krishnaiah Journal of Atmospheric and Solar Terrestrial Physics, 2000
Detection of pre-sunrise echoes at mesospheric heights Indian Journal of Radio and Space Physics, 2000
Indo-Japanese lidar observations of aerosols over a tropical latitude Indian Journal of Radio and Space Physics, 2000
Middle atmospheric temperature measurements using a ground based lidar from low latitude Indian Journal of Radio and Space Physics, 2000
Thin aerosol clouds at tropopause level Indian Journal of Radio and Space Physics, 2000
Preliminary results of equatorial wave experiment conducted from 18 Jan. 1999 to 5 Mar. 1999 with lidar at Gadanki Indian Journal of Radio and Space Physics, 2000
