Bending, buckling and vibration analyses of nonhomogeneous nanotubes using GDQ and nonlocal elasticity theory

S.C. Pradhan,J.K. Phadikar 국제구조공학회 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.33 No.2

In this paper structural analysis of nonhomogeneous nanotubes has been carried out using nonlocal elasticity theory. Governing differential equations of nonhomogeneous nanotubes are derived. Nanotubes include both single wall nanotube (SWNT) and double wall nanotube (DWNT). Nonlocal theory of elasticity has been employed to include the scale effect of the nanotubes. Nonlocal parameter, elastic modulus, density and diameter of the cross section are assumed to be functions of spatial coordinates. General Differential Quadrature (GDQ) method has been employed to solve the governing differential equations of the nanotubes. Various boundary conditions have been applied to the nanotubes. Present results considering nonlocal theory are in good agreement with the results available in the literature. Effect of variation of various geometrical and material parameters on the structural response of the nonhomogeneous nanotubes has been investigated. Present results of the nonhomogeneous nanotubes are useful in the design of the nanotubes.

Use of OSL and TL of Electronic Components of Portable Devices for Retrospective Accident Dosimetry

Pradhan, A.S.,Lee, J.I.,Kim, J.L. Trans Tech Publications, Ltd. 2013 Defect and Diffusion Forum Vol.347 No.-

<P>Growing apprehensions of radiological accidents and terroristic attacks have intensified research efforts to find materials with appropriate radiation sensitivity that are carried close to human body, are ubiquitously available and which can be used as fortuitous dosimeters in rapid determination of doses of individuals after radiation exposure. In this respect, thermoluminescence (TL) and optically stimulated luminescence (OSL) of chip cards and electronic components of personal objects have been recently evaluated by researchers in several countries. OSL and TL signal of chip cards is attributed to SiO2 grains contained in the epoxy layers used for controlling the thixotropic properties whereas the radiation induced signal in electronic components (resistors, resonators, capacitors, ICs, antenna switches, etc.) of personal objects (mobile phones, USB flash drive, MP3 players, etc.) is attributed to the ceramic contents, especially to Al2O3 based substrates.</P>

Structural, Morphological, Electrical and Impedance Spectroscopy Investigation of Pb 1/2 Ba 1/2 Ni 1/2 W 1/2 O 3 Electronic Material

S. Kalingani,Satyaprakash Narayan Das,S. K. Pradhan,S. Bhuyan,R. N. P. Choudhary 한국전기전자재료학회 2023 Transactions on Electrical and Electronic Material Vol.24 No.1

In this present study the (Pb 1/2 Ba 1/2 )(Ni 1/2 W 1/2 )O 3 , [PBNW] perovskite compound has been formulated and synthesized by adopting a solid-state reaction technique. The detailed structural, morphological, and electrical characterization has been carried out to explore its characteristics for further application in the field of electronic devices and sensors. With the help of x-ray diff raction analysis orthorhombic structure has been recognized. Dielectric, impedance spectroscopy, and a.c. conductivity analysis has been carried out through a wide range of temperatures as well as frequency (temperature range 25–500 °C, frequency range 1 kHz to 1 MHz). Presence of a single semi-circular arc from Nyquist analysis points toward the grain contribution of the sample. An equivalent circuit model has been developed to explore its electrical behavior. The activation energy, as well as the charge carrier mobility, has been estimated. Methodical studies for dielectric properties at high temperatures are accomplished for analysing electrical inhomogeneity allied with surfaces, grain boundaries, or grains, which are imperative for fundamental characterization and device fabrication.

On the use of “effective dose” ( <i>E</i> ) in medical exposures

Pradhan, A. S.,Kim, J. L.,Lee, J. I. Medknow PublicationsMedia Pvt Ltd 2012 Journal of medical physics Vol.37 No.2

Analyses of tapered fgm beams with nonlocal theory

S. C. Pradhan,A. Sarkar 국제구조공학회 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.32 No.6

In the present article bending, buckling and vibration analyses of tapered beams using Eringen non-local elasticity theory are being carried out. The associated governing differential equations are solved employing Rayleigh-Ritz method. Both Euler-Bernoulli and Timoshenko beam theories are considered in the analyses. Present results are in good agreement with those reported in literature. Beam material is considered to be made up of functionally graded materials (fgms). Non-local analyses for tapered beam with simply supported - simply supported, clamped - simply supported and clamped - free boundary conditions are carried out and discussed. Further, effect of length to height ratio on maximum deflections, vibration frequencies and critical buckling loads are studied.

Temperature and Frequency Dependent Multiferroic Features of Gadolinium Doped BiFeO3 -PbTiO3 Electronic System

S. K. Pradhan,S. N. Das,S. Bhuyan,Seshadev Sahoo,R. N. P. Choudhary 한국전기전자재료학회 2020 Transactions on Electrical and Electronic Material Vol.21 No.2

Multiferroic gadolinium (Gd) doped BiFeO 3 (BFO) and PbTiO 3 (PT) samples [(Pb 1−x Bi 0.5x Gd 0.5x )(Fe x Ti 1−x )O 3 ] with x = 0.1, 0.3, 0.5 and 0.7 are formulated by adopting the solid state reaction process. The impact of gadolinium substitution in the crystal structure, morphological behavior and electrical properties has been studied. By altering the Gd concentration in the solid solution a change in the structure is observed that is from tetragonal to rhombohedral. The size of the grain in the compounds reduces as a result of enrich in gadolinium content of the furnished sample. The subsidence of lead minimizes the toxic behavior of the material with significant improvements in dielectric response of gadolinium modifi ed BiFeO3 – PbTiO 3synthesized system. From the impedance study, the material presents negative temperature coefficient of resistance characteristics and the impedance is due to the presence of grain and grain boundary eff ect inside the materials. It is realized that the remnant polarization decreases and frequency dependent ac conductivity increases with the concentration of gadolinium in the electronic system. From conductivity study, the equipped electronic materials show non-exponential type of conductivity relaxation.

Analyses of tapered fgm beams with nonlocal theory

Pradhan, S.C.,Sarkar, A. Techno-Press 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.32 No.6

In the present article bending, buckling and vibration analyses of tapered beams using Eringen non-local elasticity theory are being carried out. The associated governing differential equations are solved employing Rayleigh-Ritz method. Both Euler-Bernoulli and Timoshenko beam theories are considered in the analyses. Present results are in good agreement with those reported in literature. Beam material is considered to be made up of functionally graded materials (fgms). Non-local analyses for tapered beam with simply supported - simply supported, clamped - simply supported and clamped - free boundary conditions are carried out and discussed. Further, effect of length to height ratio on maximum deflections, vibration frequencies and critical buckling loads are studied.

Landslide susceptibility assessment and factor effect analysis: backpropagation artificial neural networks and their comparison with frequency ratio and bivariate logistic regression modelling

Pradhan, B.,Lee, S. Elsevier Science 2010 Environmental modelling & software Vol.25 No.6

Data collection for landslide susceptibility modeling is often an inhibitive activity. This is one reason why for quite some time landslides have been described and modelled on the basis of spatially distributed values of landslide-related attributes. This paper presents landslide susceptibility analysis in the Klang Valley area, Malaysia, using back-propagation artificial neural network model. A landslide inventory map with a total of 398 landslide locations was constructed using the data from various sources. Out of 398 landslide locations, 318 (80%) of the data taken before the year 2004 was used for training the neural network model and the remaining 80 (20%) locations (post-2004 events) were used for the accuracy assessment purpose. Topographical, geological data and satellite images were collected, processed, and constructed into a spatial database using GIS and image processing. Eleven landslide occurrence related factors were selected as: slope angle, slope aspect, curvature, altitude, distance to roads, distance to rivers, lithology, distance to faults, soil type, landcover and the normalized difference vegetation index value. For calculating the weight of the relative importance of each factor to the landslide occurrence, an artificial neural network method was developed. Each thematic layer's weight was determined by the back-propagation training method and landslide susceptibility indices (LSI) were calculated using the trained back-propagation weights. To assess the factor effects, the weights were calculated three times, using all 11 factors in the first case, then recalculating after removal of those 4 factors that had the smallest weights, and thirdly after removal of the remaining 3 least influential factors. The effect of weights in landslide susceptibility was verified using the landslide location data. It is revealed that all factors have relatively positive effects on the landslide susceptibility maps in the study. The validation results showed sufficient agreement between the computed susceptibility maps and the existing data on landslide areas. The distribution of landslide susceptibility zones derived from ANN shows similar trends as those obtained by applying in GIS-based susceptibility procedures by the same authors (using the frequency ratio and logistic regression method) and indicates that ANN results are better than the earlier method. Among the three cases, the best accuracy (94%) was obtained in the case of the 7 factors weight, whereas 11 factors based weight showed the worst accuracy (91%).

Bending, buckling and vibration analyses of nonhomogeneous nanotubes using GDQ and nonlocal elasticity theory

Pradhan, S.C.,Phadikar, J.K. Techno-Press 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.33 No.2

In this paper structural analysis of nonhomogeneous nanotubes has been carried out using nonlocal elasticity theory. Governing differential equations of nonhomogeneous nanotubes are derived. Nanotubes include both single wall nanotube (SWNT) and double wall nanotube (DWNT). Nonlocal theory of elasticity has been employed to include the scale effect of the nanotubes. Nonlocal parameter, elastic modulus, density and diameter of the cross section are assumed to be functions of spatial coordinates. General Differential Quadrature (GDQ) method has been employed to solve the governing differential equations of the nanotubes. Various boundary conditions have been applied to the nanotubes. Present results considering nonlocal theory are in good agreement with the results available in the literature. Effect of variation of various geometrical and material parameters on the structural response of the nonhomogeneous nanotubes has been investigated. Present results of the nonhomogeneous nanotubes are useful in the design of the nanotubes.

Use of ubiquitous materials for the estimation of accidental exposures

Pradhan, A. S.,Kim, J. L.,Lee, J. I. Medknow PublicationsMedia Pvt Ltd 2012 Journal of medical physics Vol.37 No.3