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Kumar Pankaj,Sharma Aditya,Bishnoi Priyanka,Vij Ankush,Kumar Sandeep,Shin Hyun-Joon,Chae K. H.,Lee B. H.,Won S. O. 한국물리학회 2023 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.83 No.6
Pure and doped (Cr and Ge) ZnGa2O4 compounds are prepared using solid-state reaction method. Single-phase nature of pure and doped ZnGa2O4 compounds is investigated using X-ray difraction (XRD). XRD results indicate lower theta angle shifting, decrease in particle size and tensile strain in the doped samples. A granular morphology of amalgamated particles is seen in the SEM images. EDS results convey, practically, the same concentrations (atm%) of doped elements as used during the preparation. X-ray absorption near-edge structure (XANES) results helped to determine the valence state of elements. O K-edge XANES shows a signifcant orbital hybridization of O 2p shells with the d shells of doped atoms (i.e., Cr and Ge). Broad PL bands, of nearly the white-light emission, are observed in all of the samples. Modifcation in the PL intensity and emitted wavelengths, upon doping of Cr3+ and Ge3+ ions, are discussed through the energy transfer mechanisms and defects in the compounds.
Sandeep K. Saxena,Nagabhatla Viswanadham,M. O. GARG 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.5
A series of BEA zeolite based catalysts have been prepared and characterized by XRD, SEM, surface area, porosity and acidity methods. The catalytic properties of BEA zeolite have been improved through steam assisted dealumination reaction to achieve improvement in crystallinity, surface area, pore volume, mesopores and decrease in total acidity along with increase in strong acidity (>100 kJ/mol) measured by heat of adsorption of ammonia. All these properties collectively contributed to the formation of branched paraffins, where, the sample BEA-2 obtained by steam treatment of BEA zeolite at 500 ℃ indeed exhibited promising catalytic activity in the production of branched paraffins (responsible for higher research octane number, RON, needed for gasoline applications) from n-heptane model compound and two industrial naphtha mixed hydrocarbon feedstocks. The isomer yields obtained on naphtha-1 and naphtha-2 feedstocks are 49.3 wt.% and 52.1 wt.% respectively. The results suggest that the catalyst is potential for octane boosting (16–39 units increase in RON) of industrial hydrocarbon feedstocks to produce aromatic-free, isoparaffins-rich gasoline blending stock suitable for fuel applications.
K. Sandeep,R. S. Negi,A. S. Panicker,Alok Sagar Gautam,D. S. Bhist,G. Beig,B. S. Murthy,R. Latha,Santosh Singh,S. Das 한국기상학회 2020 Asia-Pacific Journal of Atmospheric Sciences Vol.56 No.3
Extraction of organic carbon (OC) and elemental carbon (EC) were carried out over Srinagar, India, an ecologically sensitive semi-urban site in Garhwal Himalays. The PM2.5 sampling was carried out during January to December, 2017 over the site. The OC and EC were extracted from PM2.5 samples using a thermo optical OC/EC analyzer. Highest OC and EC concncentrations were found during postmonsoon (17.67 ± 1.1 μg/m3 OC and 6.34 ± 0.75 EC) and Winter (17.31 ± 3.045 μg/m3 OC and 6.32 ± 0.585 μg/m3 EC) seasons are attributed to boundary layer dynamics and anthropogenic activities. The lower concentration of OC/ EC was observed during monsoon season (11.64 ± 1.75 μgm−3 OC and 3.46 ± 0.19μgm−3 EC) owing to wet scavenging of aerosols and minimum count of forest fire/biomass buring incidences. Both pre-monsoon and post-monsoon season concentrations are also influenced by biomass burning in the IGP (Indo-Gangetic Plain) region and forest fires in the adjecent areas. The OC/EC ratio sounds that vehicular exhaust and biomass burning are the major source of OC/EC over the site. Generation of secondary organic carbon (SOC) at the region causes variability in OC/EC ratio in different seasons. It is found that 24–32% of PM2.5 is contributed by carbonaceous aerosols (OC and EC) over Srinagar. The pivotal role of meteorology in modulating OC/ EC concentrations has been illustared in detail.
Sandeep Singh,Jeeoot Singh,K. K. Shukla 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.2
Meshless collocations utilizing Gaussian and Multiquadric radial basis functions for the stability analysis of orthotropic and cross ply laminated composite plates subjected to thermal and mechanical loading are presented. The governing differential equations of plate are based on higher order shear deformation theory considering two different transverse shear stress functions. The plate governing differential equations are discretized using radial basis functions to cast a set of simultaneous equations. The convergence of both radial basis functions is studied for different values of shape parameters. Several numerical examples are undertaken to demonstrate the accuracy of present method and the effects of orthotropy ratio of the material, span to thickness ratio of the plate, and fiber orien-tation on critical load/temperature are also presented.
A tension stiffening model for analysis of RC flexural members under service load
K. A. Patel,Sandeep Chaudhary,A.K. Nagpal 사단법인 한국계산역학회 2016 Computers and Concrete, An International Journal Vol.17 No.1
Tension-stiffening is the contribution of concrete between the cracks to carry tensile stresses after cracking in Reinforced Concrete (RC) members. In this paper, a tension-stiffening model has been proposed for computationally efficient nonlinear analysis of RC flexural members subjected to service load. The proposed model has been embedded in a typical cracked span length beam element. The element is visualized to consist of at the most five zones (cracked or uncracked). Closed form expressions for flexibility and stiffness coefficients and end displacements have been obtained for the cracked span length beam element. Further, for use in everyday design, a hybrid analytical-numerical procedure has been developed for nonlinear analysis of RC flexural members using the proposed tension-stiffening model. The procedure yields deflections as well as redistributed bending moments. The proposed model (and developed procedure) has been validated by the comparison with experimental results reported elsewhere and also by comparison with the Finite Element Method (FEM) results. The procedure would lead to drastic reduction in computational time in case of large RC structures.
Sandeep K. Saxena,Nagabhatla Viswanadham,Ala’a H. Al-Muhtaseb 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.5
Methanol value addition reaction has been studied on lab-synthesized nano-crystalline ZSM-5, Si/Al = 13 (NZ) possessing particle size of 29–51 nm and a micro-crystalline ZSM-5 (MZ) of similar atomic ratio is also taken as standard for comparison studies. The NZ sample exhibited excellent catalytic activity to produce 50.7 wt.% of high octane (Research Octane Number = 137) gasoline blending stock rich in desired toluene and xylene components, while the undesired benzene is very low, suitable for fuel applications. The superior performance of NZ to MZ catalyst reflected in three fold increase in gasoline yield and considerably high time-on-stream performance.
Rapid prediction of inelastic bending moments in RC beams considering cracking
K. A. Patel,Sandeep Chaudhary,A.K. Nagpal 사단법인 한국계산역학회 2016 Computers and Concrete, An International Journal Vol.18 No.6
A methodology using neural networks has been proposed for rapid prediction of inelastic bending moments in reinforced concrete continuous beams subjected to service load. The closed form expressions obtained from the trained neural networks take into account cracking in concrete at in-span and at near the internal supports and tension stiffening effect. The expressions predict the inelastic moments (considering the concrete cracking) from the elastic moments (neglecting the concrete cracking) at supports. Three separate neural networks are trained since these have been postulated to represent all the beams having any number of spans. The training, validating, and testing data sets for the neural networks are generated using an analytical-numerical procedure of analysis. The proposed expressions are verified for example beams of different number of spans and cross-section properties and the errors are found to be small. The proposed expressions, at minimal input data and computation effort, yield results that are close to FEM results. The expressions can be used in preliminary every day design as they enable a rapid prediction of inelastic moments and require a computational effort that is a fraction of that required for the available methods in literature.
Neural network based approach for rapid prediction of deflections in RC beams considering cracking
K. A. Patel,Sandeep Chaudhary,A.K. Nagpal 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.19 No.3
Maximum deflection in a beam is a serviceability design criterion and occurs generally at or close to the mid-span. This paper presents a methodology using neural networks for rapid prediction of mid-span deflections in reinforced concrete beams subjected to service load. The closed form expressions are further obtained from the trained neural networks. The closed form expressions take into account cracking in concrete at in-span and at near the interior supports and tension stiffening effect. The expressions predict the inelastic deflections (incorporating the concrete cracking) from the elastic moments and the elastic deflections (neglecting the concrete cracking). Five separate neural networks are trained since these have been postulated to represent all beams having any number of spans. The training, validating, and testing data sets for the neural networks are generated using an analytical-numerical procedure of analysis. The proposed expressions have been verified by comparison with the experimental results reported elsewhere and also by comparison with the finite element method (FEM). The proposed expressions, at minimal input data and minimal computation effort, yield results that are close to FEM results. The expressions can be used in every day design since the errors are found to be small.