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This article deals with the study of Bianchi type V cosmological model filled with perfect fluid in the context of f(R, T) gravity. R and T represent the Ricci scalar and trace of the energy-momentum tensor, respectively. The modified Einstein's field equations are solved under the consideration of hybrid exponential law for two cases of f(R, T). The presented models are shear free. Key words: Bianchi type V, f(R, T) gravity, perfect fluid, hybrid exponential law, equation of state. Nous etudions un modele d'univers cosmologique de type V de Bianchi rempli d'un fluide parfait, dans le contexte d'une gravite f(R, T), ou R et T sont respectivement le scalaire de Ricci et la trace du tenseur d'energie-impulsion. Nous solutionnons les equations de champ d'Einstein modifiees, sous l'hypothese d'une loi exponentielle hybride pour deux cas de f(R, T). Les modeles presentes sont sans cisaillement. [Traduit par la Redaction] Mots-cles: type V de Bianchi, gravite f(R, T), fluide parfait, loi exponentielle hybride, equation d'etat., 1. Introduction In recent times, there has been a lot of interest in the accelerating expansion of the universe. There are many questions arising in the human mind about this [...]

The present work addresses optimization of these friction stir welding process variables to maximize joint strength efficiency of welded polycarbonate sheets by using particle swarm optimization algorithm over response surface method based regression model. Initially, parametric influence on weld quality characteristics namely weld bead profile, bead geometry with associated microstructure along with micro‐hardness deviation through the weld centerline and stress‐strain behavior of the weld have been studied in detail as per full factorial design of experiments by using three different tool pin profiles such as cylindrical, square and triangular. The center point experiment i. e. tool rotational speed of 1800 min−1 and welding speed of 20 mm/min, and square tool pin profile were found to be the optimum combination with a maximum joint strength efficiency of 60.06 %. The regression model of weld ultimate tensile strength was developed by using response surface methodology which was found to be significant. Therefore, this model was further used for parametric optimization by using both response surface methodology and intelligent particle swarm optimization approaches. A slight improvement in joint strength efficiency with better optimization capability was found by using particle swarm optimization technique as compared to response surface methodology. [ABSTRACT FROM AUTHOR]

Plankton is one of the key elements for biological monitoring of riverine ecosystem. It is of paramount importance to understand plankto-environmental interaction for river ecological assessment. This article has presented an alternative model-based analytical framework to quantify plankto-environmental interactions and prediction thereof for a tropical river system. Analysis of secondary data on the Narmada River in India has made it possible to accomplish this. Hierarchical cluster analysis, based on water quality similarity, has been applied for grouping of sites. The resulted clusters slightly deviate from subjective division of the river, but their formation have been coherently ordered downstream-wise. Generalized additive modeling (GAM) with Poisson error assumption of plankton abundance has been the key modeling approach. The GAM, which has explained 66% and 88% deviance of phytoplankton and zooplankton density, respectively, has identified four (transparency, nitrate, temperature, alkalinity) out of thirteen water quality attributes in order of their relative influence on the phytoplankton and zooplankton abundance. The study has established that, in riverine system, application of GAM model under Poisson error assumption has been very effective; and the model has provided reasonably accurate prediction of plankton abundance along hydrologic distance—with noise reduction due to water quality parameters. [ABSTRACT FROM AUTHOR]

Abstract The occurrence of microplastic particles were evaluated on beaches along the Indian coast from three different locations Girgaon Mumbai (Arabian sea coast), Tuticorin, and Dhanushkodi (Bay of Bengal coast). Density separation method was adopted for isolation of microplastics from sand. Isolated microplastics were characterized using three different analytical techniques e.g. fluorescence microscopy (after staining with Nile Red), FTIR and SEM-EDS techniques. Microplastic concentrations in beach sands were from 45 ± 12 # MP kg−1 to 220 ± 50 # MP kg−1 of dry sand. The order of abundance of plastic type was polyethylene (43%) > polyethylene terephthalate (17.3%) ≈ polystyrene (17%) > polypropylene (12.3%) > Others (11%) > polyvinylchloride (1.33%), and very similar profile was observed for all monitored locations. SEM images show microplastics surfaces with characteristic cracks, suggests their polymer aging, mechanical and oxidative weathering, which was found highest for the microplastics collected from Mumbai. Graphical abstract Unlabelled Image Highlights • The order of total microplastic abundance in beach sands was megacity, industrial city followed by religious and tourist city • Fibrous shapes microplastics were observed with the majority compared to granule shape, films. • Polyethylene and polystyrene microplastics were found in dominantly in beach sand samples. • SEM images of microplastics surfaces indicates their aging, mechanical and oxidative weathering. [ABSTRACT FROM AUTHOR]

The sedimentation rates in Arctic fjords are influenced by the changes in the glacial inputs. The recent studies have indicated the retreat of glaciers due to climate change and subsequent increase in melt water outflow with high content of debris. The debris may contain natural and anthropogenically originated contaminants. The present study analysed the sedimentation rate in inner Kongsfjorden, Ny-Ålesund, Svalbard using 210 Pb/ 210 Po dating technique. The sedimentation rate ranged between 0.22 and 0.37 cm/year during the last 112 years. The average sedimentation rate obtained was 0.28 cm/y. The rate has been increased during the last 20 years and it might be due to the increased influx of glacial melt water containing debris. Metals and other elements showed an increasing trend towards the surface and observed high deposition rate since 1970s, indicating influence of industrial emissions and it can be a potential threat to Arctic biota. [ABSTRACT FROM AUTHOR]

We report levels of polycyclic aromatic hydrocarbons in sediment, seawater, fish and crab samples from Thane creek, India. Concentrations of sixteen USEPA PAH in sediments varies from 874 to 1925 ng g −1 , dry weight (dw) in winter, between 219–495 ng g −1 in summer. In seawater Σ 16 PAHs concentration during winter was recorded 706 ± 193 ng L −1 , and during summer 337 ± 79 ng L −1 . Total concentrations of PAHs in consumable portion of lizard fish, bombay duck and crab were found 156.8 ± 18 and 122 ± 24.5 ng g −1 , 117.4 ± 17.65 ng g −1 and 95.8 ± 16.2 ng g −1 , 348 ± 94.5 and 95.62 ± 31.9 ng g −1 wet weight (ww) in summer and winter respectively. PAHs concentration were compared with sediments quality guidelines viz. ERL-ERM, TEL-PEL indexes for finding ecotoxicological risk on marine organism. The ILCR values were above public screening criteria for carcinogens. [ABSTRACT FROM AUTHOR]

Being a powerful tool in modelling industrial and service operations, Petri net (PN) has been extremely used in different domains, but its application in safety study is limited. In this study, we model the gantry crane operations used for industrial activities using generalized stochastic PNs. The complete cycle of operations of the gantry crane is split into three parts namely inspection and loading, movement of load, and unloading of load. PN models are developed for all three parts and the whole system as well. The developed PN models have captured the safety issues through reachability tree. The hazardous states are identified and how they ultimately lead to some unwanted accidents is demonstrated. The possibility of falling of load and failure of hook, sling, attachment and hoist rope are identified. Possible suggestions based on the study are presented for redesign of the system. For example, mechanical stoppage of operations in case of loosely connected load, and warning system for use of wrong buttons is tested using modified models. [ABSTRACT FROM PUBLISHER]