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1

Chaotic convection of viscoelastic fluid in porous medium under G-jitter

Bhadauria B. S., Singh A., Singh M. K.

International Journal of Applied Mechanics and Engineering

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2019

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Vol. 24, no. 1

37--51

EN

The present article aims at investigating the effect of gravity modulation on chaotic convection of a viscoelastic fluid in porous media. For this, the problem is reduced into Lorenz system (non-autonomous) by employing the truncated Galerkin expansion method. The system shows transitions from periodic to chaotic behavior on increasing the scaled Rayleigh number R. The amplitude of modulation advances the chaotic nature in the system while the frequency of modulation has a tendency to delay the chaotic behavior which is in good agreement with the results due to [1]. The behavior of the scaled relaxation and retardation parameter on the system is also studied. The phase portrait and time domain diagrams of the Lorenz system for suitable parameter values have been used to analyze the system.

2

Investigations on Chemical, Thermal Decomposition Behavior, Kinetics, Reaction Mechanism and Thermodynamic Properties of Aged TATB

Singh A., Kaur G., Sarkar C., Mukherjee N.

Central European Journal of Energetic Materials

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2018

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Vol. 15, no. 2

258--282

EN

1,3,5-triamino-2,4,6-trinitrobenzene (TATB) is a kind of insensitive high explosive that can be used as an energetic material in nuclear weapon and space applications. In this work, we have studied the effect of aging on the properties of TATB from a 20 year old lot that had been in direct contact with casing and natural environment conditions. The kinetics was studied using the temperature at the maximum reaction rate (peak) and isoconversional methods from TGA and DTA data obtained at five heating rates under a nitrogen atmosphere. The properties investigated for thermal stability indicate that there is no change in the properties during prolonged exposure in natural environment conditions. The activation energy calculated by the Kissinger method was 179.9 kJ·mol−1 by DTG and the 176.9 kJ·mol−1 by DTA. The experimental results of kinetic analysis obtained by isoconversional methods are in good agreement and very close to each other. In the analysis of reaction mechanisms, the reaction models could be probably best described by a surface contraction mechanism using the Coats-Redfern and Criado methods. The thermodynamic parameters such as Gibbs free energy, enthalpy and entropy of activation were also investigated. The self-accelerating decomposition temperature (TSADT) and critical temperature for thermal explosion (Tb) were also calculated.

3

Segregation of waste at source reduces the environmental hazards of municipal solid waste in Patna, India

Singh A., Raj P.

Archives of Environmental Protection

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2018

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Vol. 44, no. 4

96--110

EN

Though Municipal Solid Waste (MSW) is a worldwide problem, the collected wastes are dumped in open dumping at landfilling sites while the uncollected wastes remain strewn on the roadside, many-a-time clogging drainage. Such unsafe and inadequate management of MSW causes spread of bacteria, viruses, particulate matter, dioxins and other harmful pollutants in the surroundings and atmosphere. Hence, due to the repeated exposure of population to these pollutants can lead to serious health problems such as Diarrhea/Dysentery, Acute Respiratory Infection (ARI), and Asthma/Chronic Respiratory Diseases (CRD). Therefore, two-phase study included secondary data on diseases caused due to environmental pollution and primary data on MSW and lack of MSW management from 127 households in urban Patna, India. The random sampling method was used for collection of primary survey data, conducted during 2015–16 in selected areas of Patna. Logistic regression model odds ratios and their 95% confidence intervals were used to show the strength of the associations among segregation of wastes at source, segregation behavior, collection bins in the area, distance of collection bins from a residential area, and transportation of MSW. The ROC is a statistical technique to validate the logistic regression method that predicts the occurrence of an event through the comparison of probability picture of an event occurrence observed by probability and the predicted probability of the same event. The area under the ROC curve is up to 0.889 extent, which reveals that the ‘segregation of waste at source’ has a very strong scope to accomplish sustainable recycling at urban Patna in order to manage waste with the overall accuracy of 92.126%, which proves a better fi t logistic regression model. Hence, this paper concludes that ‘segregation of waste at source’ helps to attain sustainable recycling which would be the most viable approach to manage MSW in Patna and would eventually reduce environmental pollutants for the public health safety.

4

Dynamics of suspended sediment load with respect to summer discharge and temperatures in Shaune Garang glacierized catchment, Western Himalaya

Kumar R., Kumar R., Singh S., Singh A., Bhardwaj A., Kumari A., Randhawa S. S., Saha A.

Acta Geophysica

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2018

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Vol. 66, no. 5

1109--1120

EN

The observed and predicted rise in temperature will have deleterious impact on melting of snow and ice and form of precipitation which is already evident in Indian Himalayan Region. The temperature-dependent entities like discharge and sediment load will also vary with the observed and predicted rise posing environmental, social and economic threat in the region. There is little known about sediment load transport in relation to temperature and discharge in glacierized catchments in Himalaya mainly due to the scarcity of ground-based observation. The present study is an attempt to understand the suspended sediment load and transportation in relation to variation in discharge and temperature in the Shaune Garang catchment. The result shows strong dependence of sediment concentration primarily on discharge (R2 = 0.84) and then on temperature (R2 = 0.79). The catchments with similar geological and climate setting were observed to have comparatively close weathering rate. The sediment load was found to be higher in the catchments in eastern and central part of Indian Himalayan Region in comparison with western part due to dominance of Indian Summer Monsoon leading to high discharge. The annual physical weathering rate in Shaune Garang catchment was found to be 411 t km−2 year−1 which has increased from 327 t km−2 year−1 in around three decades due to rise in temperature causing increase in discharge and proportion of debris-covered glacierized area.

5

Synthesis of Cu and Ce co-doped ZnO nanoparticles: crystallographic, optical, molecular, morphological and magnetic studies

Rawat M., Singh J., Singh J., Singh C., Singh A., Kukkar D., Kumar S.

Materials Science Poland

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2017

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Vol. 35, No. 2

427--434

EN

In the present research work, crystallographic, optical, molecular, morphological and magnetic properties of Zn1-xCuxO (ZnCu) and Zn1-x-yCeyCuxO (ZnCeCu) nanoparticles have been investigated. Polyvinyl alcohol (PVA) coated ZnCu and ZnCeCu nanoparticles have been synthesized by chemical sol-gel method and thoroughly studied using various characterization techniques. X-ray diffraction pattern indicates the wurtzite structure of the synthesized ZnCu and ZnCeCu particles. Transmission electron microscopy analysis shows that the synthesized ZnCu and ZnCeCu particles are of spherical shape, having average sizes of 27 nm and 23 nm, respectively. The incorporation of Cu and Ce in the ZnO lattice has been confirmed through Fourier transform infrared spectroscopy. Room temperature photoluminescence spectra of the ZnO doped with Cu and co-doped Ce display two emission bands, predominant ultra-violet near-band edge emission at 409.9 nm (3 eV) and a weak green-yellow emission at 432.65 nm (2.27 eV). Room temperature magnetic study confirms the diamagnetic behavior of ZnCu and ferromagnetic behavior of ZnCeCu.

6

Computer assisted classification framework for prediction of acute lymphoblastic and acute myeloblastic leukemia

Rawat J., Singh A., Bhadauria H. S., Virmani J., Devgun J. S.

Biocybernetics and Biomedical Engineering

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2017

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Vol. 37, no. 4

637--654

EN

Hematological malignancies i.e. acute lymphoid leukemia and acute myeloid leukemia are the types of blood cancer that can affect blood, bone marrow, lymphatic system and are the major contributors to cancer deaths. In present work, an attempt has been made to design a CAC (computer aided classification system) for diagnosis of myeloid and lymphoid cells and their FAB (French, American, and British) characterization. The proposed technique improves the AML and ALL diagnostic accuracy by analyzing color, morphological and textural features from the blood image using image processing and to assist in the development of a computer-aided screening of AML and ALL. This paper endeavors at proposing a quantitative microscopic approach toward the discrimination of malignant from normal in stained blood smear. The proposed technique firstly segments the nucleus from the leukocyte cell background and then computes features for each segmented nucleus. A total of 331 geometrical, chromatic and texture features are computed. A genetic algorithm using support vector machine (SVM) classifier is used to optimize the feature space. Based on optimized feature space, an SVM classifier with various kernel functions is used to eradicate noisy objects like overlapped cells, stain fragments, and other kinds of background noises. The significance of the proposed method is tested using 331 features on 420 microscopic blood images acquired from the online repository provided by the American society of hematology. The results confirmed the viability or potential of using a computer aided classification method to reinstate the monotonous and the reader-dependent diagnostic methods.

7

Stability analysis and internal heating effect on oscillatory convection in a viscoelastic fluid saturated porous medium under gravity modulation

Bhadauria B. S., Singh M. K., Singh A., Singh B. K., Kiran P.

International Journal of Applied Mechanics and Engineering

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2016

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Vol. 21, no. 4

785--803

EN

In this paper, we investigate the combined effect of internal heating and time periodic gravity modulation in a viscoelastic fluid saturated porous medium by reducing the problem into a complex non-autonomous Ginzgburg-Landau equation. Weak nonlinear stability analysis has been performed by using power series expansion in terms of the amplitude of gravity modulation, which is assumed to be small. The Nusselt number is obtained in terms of the amplitude for oscillatory mode of convection. The influence of viscoelastic parameters on heat transfer has been discussed. Gravity modulation is found to have a destabilizing effect at low frequencies and a stabilizing effect at high frequencies. Finally, it is found that overstability advances the onset of convection, more with internal heating. The conditions for which the complex Ginzgburg-Landau equation undergoes Hopf bifurcation and the amplitude equation undergoes supercritical pitchfork bifurcation are studied.

8

A new baroreflex sensitivity index based on improved Hilbert–Huang transform for assessment of baroreflex in supine and standing postures

Singh A., Saini B. S., Singh D.

Biocybernetics and Biomedical Engineering

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2016

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Vol. 36, no. 2

355--365

EN

The aim of this study is to propose a new baroreflex sensitivity (BRS) index using improved Hilbert–Huang transform (HHT) using weighted coherence (CW) criterion and apply it to assess baroreflex in supine and standing postures. Improved HHT is obtained by addressing the mode mixing and end effect problems associated with empirical mode decomposition which is a required step in the computation of HHT and thus mitigating the unwanted low frequency component from the power spectrum. This study was first performed on synthetic signals generated using integral pulse frequency model and further extended to real RR interval and systolic blood pressure records of 50 healthy subjects, 20 post acute myocardial infarction patients undergoing postural stress from supine to standing position. Evaluation is also performed on standard EuroBaVar database, comprising of 21 subjects, under supine and standing positions. The results are (i) enhanced values of supine-to-standing low frequency BRS index (α-LF) equal to 1.78 and high frequency BRS index (α-HF) equal to 2.48 are obtained using improved HHT compared to standard HHT (α-LF = 1.54, α-HF = 2.36) and traditional power spectral density (α-LF = 1.55, α-HF = 2.34) for healthy subjects, (ii) there is an increased rate of change of LF/HF power ratios from supine to standing positions, and (iii) number of BRS responses obtained using CW criterion are greater than those obtained by using mean coherence criterion. In conclusion, the new BRS index takes into consid-eration the non-linear nature of interactions between heart rate variability and systolic blood pressure variability.

9

Integrated biostratigraphy of the Jurassic strata of the Wagad Uplift, Kachchh, western India

Rai J., Garg S., Gupta M., Singh A., Pandey D. K., Fürsich F. T., Alberti M., Garg R.

Volumina Jurassica

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2015

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Vol. 13, no. 2

55--80

EN

An integrated study based on calcareous nannofossils, organic-walled dinoflagellate cysts, and ammonites from the Washtawa and Kanthkot formations of the Wagad Uplift have allowed a detailed documentation of the stratigraphic position of these formations within the Oxfordian and Kimmeridgian sediments of the Kachchh Basin, western India. The nannofossil assemblages from the lower part of the Nara Shale Member exposed in the Nara and Washtawa domes, the Kanthkot Ammonite Beds along the Trambau River section, and the Patasar Shale Member exposed along the Trambau River section and the Patasar Tank section in the eastern part of the Wagad Uplift belong to the NJ 14 Cyclagelosphaera margerelli Zone of the Early Oxfordian, the NJ 15a Lotharingius sigillatus Zone of the Middle Oxfordian, and the NJ 15b Cretarhabdus conicus of Early Kimmeridgian age, respectively. Zonation schemes, based on calcareous nannofossils, dinoflagellate cysts, and ammonites were calibrated highlighting their biostratigraphic potential. These studies may represent a reference biochronology for Oxfordian–Kimmeridgian age strata applicable to the Tethyan realm of which India was a part during Late Jurassic times.

10

Study of structural, morphological, optical and electroluminescent properties of undoped ZnO nanorods grown by a simple chemical precipitation

Singh A., Vishwakarma H. L.

Materials Science Poland

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2015

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Vol. 33, No. 4

751--759

EN

In this work, zinc oxide (ZnO) nanorods were obtained by a simple chemical precipitation method in the presence of capping agent: polyvinyl pyrrolidone (PVP) at room temperature. X-ray diffraction (XRD) result indicates that the synthesized undoped ZnO nanorods have hexagonal wurtzite structure without any impurities. It has been observed that the growth direction of the prepared ZnO nanorods is [1 0 1]. XRD analysis revealed that the nanorods have the crystallite size of 49 nm. Crystallite size is calculated by Debye-Scherrer formula and lattice strain is calculated by Williomson-Hall equation. Cell volume, Lorentz factor, Lorentz polarization factor, bond length, texture coefficient, lattice constants and dislocation density have also been studied. We also compared the interplanar spacings and relative peak intensities with their standard values at different angles. The scanning electron microscope (SEM) images confirmed the size and shape of these nanorods. It has been found that the diameter of the nanorods ranges from 1.52 mu m to 1.61 mu m and the length is about 4.89 mu m. It has also been observed that at room temperature ultraviolet visible (UV-Vis) absorption band is around 355 nm (blue shifted as compared to the bulk). The average particle size has also been calculated by mathematical model of effective mass approximation equation, using UV-Vis absorption peak. Finally, the bandgap has been calculated using UV-absorption peak. Electroluminescence (EL) studies show that emission of light is possible at very small threshold voltage and it increases rapidly with increasing applied voltage. It is seen that smaller ZnO nanoparticles give higher electroluminescence brightness starting at lower threshold voltage. The brightness is also affected by increasing the frequency of AC signal.

11

Comparative evaluation of performances of two versions of NCEP climate forecast system in predicting Indian summer monsoon rainfall

Acharya N., Kulkarni M., Mohanty U., Singh A.

Acta Geophysica

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2014

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Vol. 62, no. 1

199--219

EN

The operational prediction of climatic variables in monthly-toseasonal scales has been issued by National Centers for Environmental Prediction (NCEP) through Climate Forecast System model (CFSv1) since 2004. After incorporating significant changes, a new version of this model (CFSv2) was released in 2011. The present study is based on the comparative evaluation of performances of CFSv2 and CFSv1 for the southwest monsoon season (June-July-August-September, JJAS) over India with May initial condition during 1982-2009. It was observed that CFSv2 has improved over CFSv1 in simulating the observed monsoon rainfall climatology and inter annual variability. The movement of the cell of Walker circulation in years of excessive and deficient rainfall is better captured in CFSv2, as well. The observed teleconnection pattern between ISMR-sea surface temperature (SST) is also better captured in CFSv2. The overall results suggest that the changes incorporated in CFSv1 through the development of CFSv2 have resulted in an improved prediction of ISMR.21

12

Application of a Fuzzy Inference System for the Optimization of Material Removal Rate and Multiple Surface Roughness Characteristics in the Machining of GFRP Polyester Composites

Singh A., Datta S., Mahapatra S. S.

Decision Making in Manufacturing and Services

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2013

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Vol. 7, no. 1-2

19--42

EN

This paper presents a multi-objective extended optimization methodology applied in the machining of a randomly oriented GFRP rod. Design of Experiment (DOE) has been selected based on a L9 orthogonal array design with varying process control parameters like: spindle speed, feed rate and depth of cut. Multiple surface roughness parameters of the machined FRP product along with the Material Removal Rate (MRR) of the machining process have been optimized simultaneously. The Fuzzy Inference System (FIS) has been proposed for providing feasible means for the meaningful aggregation of multiple objective unctions into an equivalent single performance index (MPCI). This Multi-Performance Characteristic Index (MPCI) has been optimized using the Taguchi method. The approach adapted here is capable of overcoming limitations/assumptions of existing optimization methodologies available in the literature.

13

Bedform effect on the reorganization of surface and subsurface grain size distribution in gravel bedded channels

Singh A., Guala M., Lanzoni S., Foufoula-Georgiou E.

Acta Geophysica

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2012

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Vol. 60, no. 6

1607-1638

EN

Quantification of river bedform variability and complexity is important for sediment transport modeling as well as for characterization of river morphology. Alluvial bedforms are shown to exhibit highly nonlinear dynamics across a range of scales, affect local bed roughness, and vary with local hydraulic, hydrologic, and geomorphic properties. This paper examines sediment sorting on the crest and trough of gravel bedforms and relates it to bed elevation statistics. The data analysed here are the spatial and temporal series of bed elevation, grain size distribution of surface and subsurface bed materials, and sediment transport rates from flume experiments. We describe surface topography through bedform variability in height and wavelength and multiscale analysis of bed elevations as a function of discharge. We further relate bedform migration to preferential distribution of coarse and fine sediments on the troughs and crests, respectively, measuring directly surface and subsurface grain size distributions, and indirectly the small scale roughness variations as estimated from high resolution topographic scans.

14

Chelating sorbent for heavy mental ions obtained by modification of an anion-exchange resin with diethyldithiocarbamate

Singh A., Srivastava A.K.

Chemia Analityczna

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2009

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Vol. 54, No. 2

257-267

EN

A new chelating sorbent for heavy metal ions was prepared by modification of a strongly basic Ceralite IR 400 resin with diethyldithiocarbamate (DDTC). Ceralite IR 400-DDTC resin was characterized on the basis of FTIR spectra and sorption capacity. The breakthrough and overall capacities for Cu2+, Pb2+, Zn2+, Cd2+, Co2+ Ni2+, Hg2+, Mn2+ and Fe2+ were determined. Distribution coefficients (Kd) were studied at pH 1,2,4, and 6. The resin retained the tested heavy metal ions, while no sorption was observed for alkali and alkaline earth metal ions in the investigated pH range. The resin exhibited the highest breakthrough capacity (0.82 mmol g-1dry resin) and selectivity (highest K.d) for Cu2+. Sorption properties of the resin should be ascribed to the contribution of the bridging sulfur of DDTC to selective coordination of metal ions. On the basis of Kd values, quantitative separations of Cu2+ from Zn2+, Cd2+ and Mn2+, and Zn2+ from Fe2+and Hg2+ were achieved. The column was also used for removal and recovery of Cu2+ from water samples. The sorption behavior followed the Freundlich adsorption isotherms.

PL

Przygotowano nowy sorbent chelatujący jony ciężkich metali przez modyfikację silnie zasadowego anionitu Ceralitu 1R 400 za pomocądietyloditiokarbaminianu (DDTC). Jonit Ceralit IR 400-DDTC scharakteryzowano na podstawie widm FTIR oraz pomiarów zdolności sorpcyjnej. Wyznaczono całkowite pojemności i pojemności do przebicia dla Cu2+, Pb2+, Zn2+, Cd2+, Co2+, Ni2+, Hg2+, Mn2+ i Fe3+. Badano także współczynniki podziału (Kd) przy pH l, 2,4 i 6. Jonit zatrzymywał badane jony metali ciężkich, natomiast nie zaobserwowano żadnej sorpcji jonów metali alkalicznych i ziem alkalicznych w badanym zakresie pH. Największą pojemność do przebicia (0,82 mmol g-1 suchego jonitu) i najlepszą selektyw-ność (najwyższa warość Kd) obserwowano dla jonów Cu2+ . Sorpcyjne właściwości jonitu można przypisać oddziaływaniu mostka siarkowego DDTC na selektywne wiązanie jonów metalicznych. Korzystając z różnic wartości Kd przeprowadzono selektywne oddzielanie Cu2+ od Zn2+, Cd2+ od Mn2+ oraz Zn2+od Fe3+ i Hg2+. Kolumnę z jonitem stosowano także do odzysku Cu2+ z próbek wody. Zachowanie sorpcyjne jonitu można było dobrze opisać za pomocą izotermy adsorpcji Freundlicha.

15

Hisslers observed during daytime in a low latitude ground station

Singh K., Patel R., Kumar B., Altaf M., Ganai P., Singh A., Singh R., Lalmani

Acta Geophysica

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2009

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Vol. 57, no. 2

536-547

EN

The observation of hisslers during daytime at low latitude station Jammu, India, is reported. The hissler elements are quasi-periodic falling tones observed during the period of hiss activity and appear in minutelong sequences with average spacing between individual elements of the order of 0.15 s. Hissler elements exhibit almost no dispersion and no complex internal structure in slope and intensity, and successive hissler elements do not overlap in time. It seems that the reported hisslers might have propagated in prolongitudinal mode.