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X-ray Absorption and Emission Spectroscopic Studies of BiMn2-xTixO5 (0 ≤ x ≤ 0:5)
K. H. Chae,P. Thakur,황정남,G. S. Chang,D. K. Shukla,S. Mollah,Ravi Kumar 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.3
The electronic structure of the multiferroic BiMn2-xTixO5(0 ≤ x ≤ 0:5) system was studied by using X-ray absorption spectroscopy (XAS) and X-ray emission spectroscopy (XES). The polycrystalline bulk BiMn2-xTixO5 samples were synthesized using a conventional solid-state reaction technique. XAS and XES spectroscopic studies on the O K-, Mn K-, L3;2- and Ti L3;2-edges of the BiMn2-xTixO5 samples and of the reference compounds were performed and the results were compared in order to determine the exact chemical states of functioning ions. The O K-edge XAS and XES results demonstrate a competition between the Mn 3d and the Ti 3d orbitals on hybridizations with the O 2p orbital. The Mn K- and Mn L3;2-edge XAS spectra suggest that the Mn3+ /Mn4+ ratio increases with increasing Ti doping and drives the system towards octahedral symmetry. On the other hand, Ti ions remain at 4+ states for all compositions, as shown by the Ti L-edge XAS. Here, we present and discuss the detailed electronic structures of the BiMn2-xTixO5 samples.
Shukla, Sanjay K.,Bathurst, Richard J. Techno-Press 2012 Geomechanics & engineering Vol.4 No.3
This paper presents the derivation of an analytical expression for the dynamic active thrust from c-${\phi}$ (c = cohesion, ${\phi}$ = angle of shearing resistance) soil backfill on rigid retaining walls with wall friction and adhesion. The derivation uses the pseudo-static approach considering tension cracks in the backfill, a uniform surcharge on the backfill, and horizontal and vertical seismic loadings. The development of an explicit analytical expression for the critical inclination of the failure plane within the soil backfill is described. It is shown that the analytical expression gives the same results for simpler special cases previously reported in the literature.
Shukla, R.K.,Tilak, A.R.,Kumar, C.,Kant, S.,Kumar, A.,Mittal, B.,Bhattacharya, S. Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.5
Background: Susceptibility to lung cancer has been shown to be modulated by inheritance of polymorphic genes encoding cytochrome P450 1A1 (CYP1A1) and glutathione S transferases (GSTM1 and GSTT1), which are involved in the bioactivation and detoxification of environmental toxins. This might be a factor in the variation in lung cancer incidence with ethnicity. Materials and Methods: We conducted a case-control study of 218 northern Indian lung cancer patients along with 238 healthy controls, to assess any association between CYP1A1, GSTM1 and GSTT1 polymorphisms, either separately or in combination, with the likelihood of development of Lung cancer in our population. Results: We observed a significant difference in the GSTT1 null deletion frequency in this population when compared with other populations (OR=1.87, 95%CI: 1.25-2.80-0.73, P=0.002). However, GSTM1 null genotype was found associated with lung cancer in the non-smoking subgroup. (P=0.170). Conclusions: Our study showed the GSTT1 null polymorphism to be associated with smoking-induced lung cancer and the GSTM1 null polymorphism to have a link with non-smoking related lung cancer.
Analysis of building frames with viscoelastic dampers under base excitation
Shukla, A.K.,Datta, T.K. Techno-Press 2001 Structural Engineering and Mechanics, An Int'l Jou Vol.11 No.1
A frequency domain response analysis is presented for building frames passively controlled by viscoelastic dampers, under harmonic ground excitation. Three different models are used to represent the linear dynamic force-deformation characteristics of viscoelastic dampers namely, Kelvin model, Linear hysteretic model and Maxwell model. The frequency domain solution is obtained by (i) an iterative pseudo-force method, which uses undamped mode shapes and frequencies of the system, (ii) an approximate modal strain energy method, which uses an equivalent modal damping of the system in each mode of vibration, and (iii) an exact method which uses complex frequency response function of the system. The responses obtained by three different methods are compared for different combinations of viscoelastic dampers giving rise to both classically and non-classically damped cases. In addition, the effect of the modelling of viscoelastic dampers on the response is investigated for a certain frequency range of interest. The results of the study are useful in appropriate modelling of viscoelastic dampers and in understanding the implication of using modal analysis procedure for building frames which are passively controlled by viscoelastic dampers against base excitation.
Shukla Vikram,Gera Bhuvaneshwar,Ganju Sunil,Varma Salil,Maheshwari N.K.,Guchhait P.K.,Sengupta S. 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.11
Hydrogen mitigation using Passive Autocatalytic Recombiners (PARs) has been widely accepted methodology inside reactor containment of accident struck Nuclear Power Plants. They reduce hydrogen concentration inside reactor containment by recombining it with oxygen from containment air on catalyst surfaces at ambient temperatures. Exothermic heat of reaction drives the product steam upwards, establishing natural convection around PAR, thus invoking homogenisation inside containment. CFD models resolving individual catalyst plate channels of PAR provide good insight about temperature and hydrogen recombination. But very thin catalyst plates compared to large dimensions of the enclosures involved result in intensive calculations. Hence, empirical correlations specific to PARs being modelled are often used in integral containment studies. In this work, an experimentally validated CFD model of PAR has been employed for developing an empirical correlation for Indian PAR. For this purpose, detailed parametric study involving different gas mixture variables at PAR inlet has been performed. For each case, respective values of gas mixture variables at recombiner outlet have been tabulated. The obtained data matrix has then been processed using regression analysis to obtain a set of correlations between inlet and outlet variables. The empirical correlation thus developed, can be easily plugged into commercially available CFD software.
An Approach to Develop a Compact Transmission Line Tower with Special 8-Legged Confi guration
Veerendra K. Shukla,M. Selvaraj,R. Ramesh Babu 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.1
For transmission of electricity from power generation plant to substations, many types of structures are being used. The main function of these structures is to support the power conductors and earth-wire. 4-legged steel lattice tower is one of these structures, which is widely used for this purpose. The main drawback of a 4-legged lattice tower is its larger base width, which occupy very large area. Nowadays, in many countries, adequate land is not available to consider such large land occupying towers. In these situations, using monopoles became common practice. But the monopoles are much costlier than the 4-legged lattice towers. To avoid the use of monopoles and to reduce the base width at the same time, in the present work, an approach has been adopted to use a special lattice type structure with eight legs. A 220 kV multi-circuit suspension tower with 0°–2° deviation has been considered for present study. The detail explanations, like, tower geometry, load calculations, analysis and design of the proposed structure has been covered in the paper. It has been observed that land requirement can be considerably minimized by use of the proposed 8-legged tower. The cost of the 8-legged tower is slightly more than a 4-legged tower but much lesser than that of monopoles as the total weight of steel required is very less as compared to monopole. The results obtained from the study of the proposed tower have been compared with 4-legged tower and monopole. This paper discusses the feasibility of using the transmission line tower with 8-legs. The paper also discusses a comparative study of cost, right of way, height and base width of 4-legged tower, monopole and proposed 8-legged tower .
Ferromagnetic Properties of Bulk Fe-doped CeO2 Dilute Magnetic Semiconductors
S. K. Sharma,M. Knobel,C. T. Meneses,샤런드라쿠마르,Y. J. Kim,B. H. Koo,이찬규,D. K. Shukla,Ravi Kumar 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.3
Polycrystalline Fe-doped Ce1−xFexO2−δ has been fabricated by using the standard solid state reaction technique in the concentration range 0 ≤ x ≤ 0.05. Reitveld refinement of the X-ray diffraction patterns shows a pure CeO2 phase when x ≤ 0.03, and the appearance of a secondary impurity phase of Fe2O3 beyond that. Furthermore, by doping Fe into CeO2 powder, the ferromagnetism can be significantly enhanced to a maximum value for x = 0.03, but degrades quickly with further doping. Magnetization results reveal that the large room-temperature ferromagnetism observed in Fe-doped CeO2 powder originates from a combined effect of oxygen vacancies and transition metal doping.