Search published articles
Showing 3 results for Mondal
Priyankar Mondal, Krishna Karmakar, Moumi Ganguly, Debamitra Chatterjee, Sunil Kr. Ghosh,
Volume 9, Issue 2 (6-2023)
Abstract
A vast number of tropical and subtropical mites belong to the family Tarsonemidae Canestrini & Fanzago, 1877, with the tribe Tarsoenmini under subfamily Tarsoneminae having the most diverse assemblage. In order to better understand the distribution, community structure, and host specificity of these mites, it is important to investigate the Tarsonemini mite fauna of India, particularly in the highly biodiverse state of West Bengal. A total of 1154 mite specimens were obtained from 69 distinct plant species belonging to 44 families and distributed over six agroclimatic zones in West Bengal. The mites were classified into 8 distinct genera and 38 morphospecies. We developed bipartite trophic networks for Tarsonemini mites for the first time to show how these different communities of these mites are associated to various host plant species in six different agroclimatic zones. Different network descriptors such as Connectance, H2, Niche Overlap and Robustness were calculated from the mite-plant networks of six agroclimatic zones. Northern Hill Zone had the highest diversity followed by New Alluvial and Teesta-Terai Zone whereas, Red Laterite Zone had the least diversity of mite species. More than 70% Tarsonemini mites were found as generalist plant inhabitants which is consistent with their epiphytotic microbivorous feeding strategy.
Volume 14, Issue 7 (10-2014)
Abstract
Analytical and finite element models predict the elastic modulus of CNT-polymer nanocomposites greater than experimental results. This paper presents a theoretical full continuum model to define the upper and lower thresholds with small variations for elastic modulus in polymer nanocomposites, which the experimental results always place between these thresholds. For this purpose, the governing elasticity equations in polar coordinates have been solved for nanocomposite representative volume element (RVE) with shear-lag model by assuming perfect bond condition between CNT and matrix. In addition, the nanocomposite elastic modulus in perfect bond and debonding conditions between nanotube and matrix is calculated using finite element method in ANSYS software which confirms the accuracy of theoretical results. Also the obtained analytical and FEM results are compared with available experimental results, which indicates that the value of experimental results is always between the upper and lower thresholds of analytical and FEM results.finally by surveying the axial and von-mises stress in the matrix region, the new way for defining the elastic modulus of new nanocomposites with analytical method is proposed here which reduce the cost of experimental research.
Volume 20, Issue 4 (April 2020)
Abstract
In this research, the thermo-mechanical behavior of SWCNTs reinforced polymer has been characterized using an analytical method based on semi-continuum modeling. For this reason, a representative volume element of CNT reinforced polymer with cyclic symmetry boundary condition is used while the nanotube reinforcement is modeled in nanoscale and its surrounding polymer is considered as a continuum environment. Applying the cyclic symmetry boundary conditions in the problem-solving procedure causes satisfactory agreement between the results of the analytical method and the actual conditions. The interphase between the nanotube and polymer is also modeled using the cohesive stresses and the mechanical properties extracted from the Vander-Waals forces between the atoms of nanotube and polymer. In general, the thermal residual stresses in polymer/CNT nanocomposites can occur due to the significant differences between the thermal expansion coefficient of polymer and CNT. In the present paper, the semi-continuum modeling has been firstly explained and then the role of some effective parameters such as volume fraction, aspect ratio, and temperature change on the residual thermal stresses has been studied. Although, based on some available researches in macro scale, it seems that adding the CNTs to polymer leads to decreasing the thermal expansion of nanocomposite and consequently decreasing its thermal residual stresses. However, the results of this paper show that by inappropriate selection of some parameters such as the volume fraction and aspect ratio of nanotubes and also the temperature change, the residual thermal stresses increase between the polymer and nanotube which it can weaken the material strength.
