Dr Vishal Chauhan - Academia.edu (original) (raw)

Papers by Dr Vishal Chauhan

Energy Sources, Part A: Recovery, Utilization, and Environmental Effects

Environmental Science: Advances

Planetary ball milling assisted piezocatalysis for water cleaning application.

Materials Today: Proceedings

543-556Ground based observations have been carried out for ultra low frequency (ULF) precursors o... more 543-556Ground based observations have been carried out for ultra low frequency (ULF) precursors of earthquakes at four different stations in India, namely Agra (geographic lat 27°N, long 78°E), Guttu (lat 31.53°N, long 78.75°E), Shillong (lat 25.92°N, long 91.88°E) and Kolhapur (lat 16.40°N, long 74.15°E) using identical 3-component search coil magnetometers (f = 0.01-30 Hz) obtained from Lviv Centre of Space Research, Ukraine. An offline analysis of the combined data has been carried out in relation to a major earthquake of magnitude M=7.9 occurred in the neighbouring country China (lat 31°N, long 103.32°E, depth=19 km) under the National Program of Earthquakes Precursors (NPEP) launched in India since May 2009. The results of the analysis show occurrence of amplitude anomalies as precursors whose amplitudes decrease with distance. The precursor periods range between 2 and 5 days and are large for the stations nearer to epicenter. A graphical determination of location of the epicen...

International Journal Of Innovation In Engineering Research & Management UGC APPROVED NO. 48708, EFI 5.89, WORLD SCINTIFIC IF 6.33, 2020

Current Science, 2021

Various geophysical parameters including soil radon (222 Rn) are being continuously monitored at ... more Various geophysical parameters including soil radon (222 Rn) are being continuously monitored at Ghuttu, Garhwal Himalaya, India since 2007 as a part of earthquake precursor studies. To analyse the earthquake precursory changes in soil radon, it is essential to clean the soil radon data from other effects. For this, we used data for the period of nine years from 2011 to 2019 and assessed the relationship of soil radon with five other parameters using regression analysis. These parameters are water level, atmospheric pressure, rainfall, air temperature and soil temperature at 10 m depth. We also added one more parameter, i.e. the difference of air temperature (T out) and soil temperature at 10 m depth (T in). From the observed six parameters, four showed strong correlation with soil radon. These are (i) water level (correlation coefficient (CC) =-0.9), (ii) atmospheric pressure (CC = 0.6), (iii) air temperature (CC =-0.6) and (iv) temperature difference (T out-T in ; CC = 0.5). For regression analysis, data during the period 2011-2014 were used for training, while data during 2015-2019 were used for testing purpose. Based on different models, the one developed using all the six input parameters suggests lowest errors and highest correlation. The observed values of root mean square error, mean absolute error and CC were 0.332, 0.281 and 0.931 respectively. The regression coefficients obtained from this model were used to calculate the theoretical radon and residuals. By this approach, the effects of hydrological and atmospheric parameters were found to be reduced to a great extent.

Blood, 2017

Introduction- Acute Promyelocytic leukemia (APML) needs to be suspected early so that All-Trans R... more Introduction- Acute Promyelocytic leukemia (APML) needs to be suspected early so that All-Trans Retinoic Acid (ATRA) therapy can be started as soon as possible. Flow cytometry shows absence of CD34 and HLADR in most cases and so can aid in diagnosis along with the usual morphological clues. However, it may have confusing patterns as in hypogranular APML and sometimes may be positive for HLA- DR and CD34. RT-PCR for detection of characteristic APML translocations (t(15;17),t(17;17) and others) is gold standard for APML diagnosis which is time consuming and often not possible especially in resource limited areas. Cytochemical MPO stain is a robust laboratory test that can be a valuable aid to morphology in early diagnosis of APML. In this study, the role of cytochemical MPO was evaluated for early diagnosis of APML. Method- This study included all the cases of APML that were diagnosed in a tertiary care center in India from May 2011 to May 2014. Cytochemical stains (MPO, Non- specific...

Lecture Notes in Mechanical Engineering, 2019

Over the past few decades, the world has started moving towards renewable resources of energy fro... more Over the past few decades, the world has started moving towards renewable resources of energy from non-renewable resources for meeting today’s energy demand. The solar energy is available abundant in nature and easy to harvest it, and provides a natural solution to move ahead in fulfilling the energy requirement. The solar photovoltaic cells convert solar energy to electrical energy. In general, the regular PV module cell converts nearly about 5–18% of the incidental solar radiation into electricity, and in order to maintain energy balance nearly 60% of incidental radiations are converted in the form of heat energy and with scientific and experimental analysis; it is already pre-determined that with increase in internal PV cell temperature there is an exponential decrease in electrical efficiency of the solar cell gradually with this alternate cooling and superheating process over a time period thermal stresses are formed in solar cell which eventually degrades the cell. A practical way of marginally increasing the output efficiency of solar PV cell is to decrease the operating and surrounding temperature of solar PV, which can be achieved by maintaining a stipulated temperature when solar photovoltaic cell is in operation. Therefore, in the following work, a novel passive technique of cooling has been introduced by basic principles of evaporation using sand dunes concept of cooling and will be investigated experimentally.

Investigative Ophthalmology & Visual Science, 2011

2017 8th International Conference on Computing, Communication and Networking Technologies (ICCCNT), 2017

Over the years, use of Online Social Networks (OSNs) has exploded and thus, causing a need of stu... more Over the years, use of Online Social Networks (OSNs) has exploded and thus, causing a need of studying and understanding users' behavior online. The excessive use of online social networking causes a great increase in anomalies. Anomalies in OSNs can signify irregular and often illegal behavior. Detection of such anomalies has been used to identify malicious individuals, including spammers, sexual predators and online fraudsters. For detecting the anomalies dataset of Twitter network is used and analyzed for user behavior via analyzing their tweets to find whether it is an anomalous or not.

2018 14th International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob), 2018

Electric Vehicles (EVs) are being increasingly seen as an eco-friendly alternative to conventiona... more Electric Vehicles (EVs) are being increasingly seen as an eco-friendly alternative to conventional internal combustion vehicles. EVs require periodic charging of their batteries and fixed charging stations (FCSs) have been used commonly to charge EV batteries. However, FCSs may not be able to charge many EVs during increased demands. Mobile charging stations (MCS) have been proposed for charging EVs at different spots, with an MCS carrying batteries travelling to the EV to charge its batteries. In this paper, we propose a framework for temporarily increasing the capacity of FCSs by scheduling MCSs to service additional EVs during increased demand. The problem of scheduling the MCSs to different FCSs based on EV charging demands is formulated, and is shown to be NP-hard. Two offline heuristic algorithms to solve the problem are proposed. Detailed simulation on a real-world map is presented to show that the algorithms perform well in realistic scenarios.

Applied Radiation and Isotopes, 2020

Assessment of Rn-222 continuous time series for the identification of anomalous changes during mo... more Assessment of Rn-222 continuous time series for the identification of anomalous changes during moderate earthquakes of the Garhwal Himalaya, Applied Radiation and Isotopes (2020), doi:

Biomass Conversion and Biorefinery, 2019

Conventional coal-based technologies are experiencing several disadvantages due to its high ash c... more Conventional coal-based technologies are experiencing several disadvantages due to its high ash content as well as a significant amount of greenhouse gas emission. Focus is shifting towards the utilization of renewable resources like biomass. The efficient use of coal and biomass in a clean manner has been the driving force in developing gasification technologies. In the present investigation, an effort has been made to study the gasification performance of selected coal with two types of biomass, namely rice husk and sawdust in different proportions in a pilot-scale bubbling fluidized bed gasifier. Gasification was conducted with a mixture of air and steam at a temperature between 900-950°C and atmospheric pressure. Mainly, three blends were prepared by adding 10, 20, and 40% of biomass with the selected coal. It was found that up to 40% of biomass loading, gasifier is operated in a trouble-free manner without the formation of tar or any agglomerate by maintaining proper fluidization with smooth and controlled variation in the process parameters like temperature, airflow, and steam flow rate. Due to the synergistic influence between coal and biomass, overall carbon conversion, gas yield, and gas heat value were found to increase with increasing biomass loading.

NRIAG Journal of Astronomy and Geophysics, 2018

Co-seismic ionospheric disturbances (CIDs) due to different source characteristic earthquakes are... more Co-seismic ionospheric disturbances (CIDs) due to different source characteristic earthquakes are investigated through GPS-derived vertical total electron content (VTEC). We investigated VTEC changes related with Moderate, Strong, Major and Great earthquakes occurred at different tectonic settings in both Himalaya and non-Himalayan regions. The VTEC and its anomalies are computed using GPS data obtained from the local network of GPS stations in Himalaya with the IGS stations surrounding the epicentre region. Irrespective of the source characteristics, significant CIDs are observed during Major and Great earthquakes, namely; (i) the Mw 7.8, 25th April 2015 Gorkha earthquake, (ii) the Mw 7.6, 8th October 2005 Kashmir earthquake, and (iii) the Mw 8.6, 28th March 2005 Nias-Simeulue earthquake. The VTEC anomalies due to the Gorkha event are observed 21.15 min after the earthquake origin time and continued till 22.78 min with the amplitude range from −0.530 to 0.517 (± 0.11) TECU. CIDs associated with the Kashmir earthquake are noticed only at two GPS sites (NADI and PAN2) roughly after 23 min of the earthquake occurrence. But, it continued around 14 min with the amplitude range from −0.12 to 0.177 TECU (± 0.02 TECU = 1σ). However, for the case of Ocean-Island Arc Nias-Simeulue earthquake, anomalous CIDs were observed only at GPS site NTUS, where the disturbances started around 25.58 min later and continued around 17.92 min with amplitude range from −0.077 to 0.058 TECU (± 0.02 TECU = 1σ). We inferred that the CIDs originated because of earthquakes in Himalaya have relatively larger VTEC magnitudes (> 15 TECU) that propagates faster in reaching and registering in the ionospheric layers compared with the non-Himalayan earthquakes. Secondly, different lithospheric-ionospheric coupling mechanism is operating in transferring the seismic energy, which originated from the Continent-Continent and the Tsunami genic Ocean-Island Arc collision zone, to the ionosphere.

Indian Journal of Radio and Space Physics

The DEMETER (Detection of Electromagnetic Emissions Transmitted from Earthquake Regions) satellit... more The DEMETER (Detection of Electromagnetic Emissions Transmitted from Earthquake Regions) satellite data have been analysed for a period of three and half months from 01 September to 16 December 2010 in search of whistlers and VLF emissions and their ground observations at low latitudes. The quick look data show intense sporadic bursts mostly in the Instrument Champ Electrique (ICE) channel of the satellite. These bursts are analysed using MATLAB software for the nighttime passes of upgoing orbits in the latitude range 20°-50°. The analysis shows records of large number of first component of magnetospherically reflected (MR) whistlers, mostly when the satellite is in low latitude ionosphere. These whistlers, together with normal whistlers observed in the satellite, are not observed on the ground as revealed by simultaneous ground observations at low latitude station Agra. This confirms them to be non-ducted whistlers which are reflected and observed in the ionosphere and magnetospher...

Present paper includes performance study of a vertical Kaplan turbine using CFD analysis. The ana... more Present paper includes performance study of a vertical Kaplan turbine using CFD analysis. The analysis is performed for single phase containing only water for steady state condition. The turbine performance is analyzed at BEP and part load points using CFD and it shows that the performance obtained is quite satisfactory for the BEP and part load conditions. Therefore, it can be concluded that CFD can be used as an effective tool during design cycle to reduce the time and cost and to enhance the product performance.

Ferroelectrics, 2015

This article deals with selection and performance evaluation of various piezoelectric materials f... more This article deals with selection and performance evaluation of various piezoelectric materials for active vibration control (AVC) application. Finite element method is used to assess the relative importance of materials properties (Young's Modulus (E), piezoelectric constants (e31), dielectric constant (ε), density (ρ) and Poisson's ratio (υ)) for sensor and actuator applications which are eventually used in active vibration control. Analytical hierarchy process (AHP) is finally used to assign weights to all the properties understudy. Rankings made by multiple attribute decision matrix (MADM) approach show good agreement with finite element (FE) simulation results. The numerical simulations reveals the superior performance of K0.5Na0.5NbO3-LiSbO3-CaTiO3(KNN-LS-CT (1 wt. %)) as sensor followed by KNN-LS-CT (2 wt. %) and K0.475Na0.475Li0.05 (Nb0.92Ta0.05Sb0.03) O3 (KNLNTS). For actuator, Pb [ZrxTi1−x] O3 (PZT1) demonstrates the superior performance followed by KNLNTS and KNN-LS-CT (1 wt. %). The lead-free piezoelectric materials are potential candidate to replace lead-based piezoelectric materials for active vibration control application.

Polymer Composites, 2015

ABSTRACT The article deals with finite element study of 1–3 composites made of piezoceramic fiber... more ABSTRACT The article deals with finite element study of 1–3 composites made of piezoceramic fibers embedded in epoxy. The study focuses on evaluation of effective properties of piezoelectric fiber composites using representative volume element method. The physical properties deduced are further used for analyzing sensing and actuation characteristics of unimorph cantilever beam. K0.5Na0.5NbO3-LiSbO3(KNN-LS), KNNLS doped with 1 wt% CaTiO3 [KNN-LS-CT (1 wt%)], K0.475Na0.475Li0.05(Nb0.92Ta0.05Sb0.03)O3 (KNLNTS), 0.885 (Bi0.5Na0.5)TiO320.05(Bi0.5K0.5)TiO320.015 (Bi0.5Li0.5)TiO3 20.05 BaTiO3(BNKLBT) and lead zirconate titanate (Pb[ZrxTi12x]O3) (PZT) are embedded in epoxy matrix to form 1–3 piezocomposites. K0.475Na0.475Li0.05(Nb0.92Ta0.05 Sb0.03)O3 (KNLNTS) shows excellent performance than other composites under study. It can be concluded that KNLNTS (lead-free piezoelectric material) is a potential candidate which can replace lead based PZT for smart structure applications.