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© The Author(s) 2020. Wireless sensor network is a hot research topic with massive applications in different domains. Generally, wireless sensor network comprises hundreds to thousands of sensor nodes, which communicate with one another by the use of radio signals. Some of the challenges exist in the design of wireless sensor network are restricted computation power, storage, battery and transmission bandwidth. To resolve these issues, clustering and routing processes have been presented. Clustering and routing processes are considered as an optimization problem in wireless sensor network which can be resolved by the use of swarm intelligence–based approaches. This article presents a novel swarm intelligence–based clustering and multihop routing protocol for wireless sensor network. Initially, improved particle swarm optimization technique is applied for choosing the cluster heads and organizes the clusters proficiently. Then, the grey wolf optimization algorithm–based routing process takes place to select the optimal paths in the network. The presented improved particle swarm optimization–grey wolf optimization approach incorporates the benefits of both the clustering and routing processes which leads to maximum energy efficiency and network lifetime. The proposed model is simulated under an extension set of experimentation, and the results are validated under several measures. The obtained experimental outcome demonstrated the superior characteristics of the improved particle swarm optimization–grey wolf optimization technique under all the test cases.

Nowadays, automotive, packaging and sport equipment industries are using natural fibre based composite materials as they are cheap, abundantly available and having a lot of ecological advantages. The main objective of this paper is to introduce a new concept of fibre twisting and to investigate the effect of twisting and the fibre orientation on the mechanical properties of bio degradable green composites. Here, the composites are fabricated by vacuum assisted compression molding technique in which the problems of hand lay process are eliminated. Here, two fibers namely twisted neem and twisted kenaf are sandwiched between layers of glass fibres to enhance the stiffness and strength of the laminates. Initially, the fibers are alkalized to increase the mechanical properties. The result shows that there is a significant improvement in mechanical properties of composites due to the presence of twisted fibers. It also shows the influence of fiber orientation on mechanical properties.

Fission tracks in phosphates from one gas-poor chondrite and three gas-rich ones are studied to determine their thermal history and brecciation time scales. Model fission track ages are calculated for given track densities due to Pu-244 and U-238; track densities and uranium measurements for whitlockite are shown, and possible sources of the tracks are mentioned. Details of track density and uranium measurements are discussed for each meteorite separately. Whitlockites from all the meteorites give model fission track ages of 4.4 Gyr assuming a Pu/U ratio at 4.55 Gyr of 0.045. The final brecciation event definitely did not reset the track clock in phosphates of one meteor and probably not in another two. It is concluded that the observed fission track ages date the end of metamorphic cooling in the meteorite parent bodies and support the planetesimal model for the formation of xenolithic chondrites.

Four possible scenarios relating the proto-solar cloud to the 'last-minute' supernova presumed responsible for the isotopic anomalies in Allende and other meteorites are considered. The probability that a chance supernova occurred close enough to an already-collapsing proto-solar cloud to inject sufficient matter is extremely small, even if the sun formed in a region of enhanced supernova activity such as Orion OB1. The ambient level of Al-26 inside a molecular cloud in Orion is also apparently too low to account for the meteorite data, unless the supernova ejecta accumulates at the edges of the cloud and star formation occurs there preferentially. Two modes of supernova-induced star formation are discussed. In one, the supernova shock collapses a preexisting cloud; in the other, stars form within the snowplow shell of the supernova. Canis Major R1 and Monoceros R1 are possible present-day examples of such star formation regions.

With the transmission electron microscope, we have made detailed studies of the track density gradients and irradiation geometries of track-rich grains and chondrules in sections of Fayetteville and Kapoeta. We have made the same type of studies in sections of lunar breccias and grains from lunar soil for comparison. A substantial fraction (50–90 per cent) of the meteoritic track-rich grains and chondrules show evidence of having been irradiated anisotropically in their different faces, as would be expected for irradiation on the surface of a parent body. Our observations thus support the hypothesis that the irradiation of these grains and chondrules took place on the regoliths of asteroidal-sized bodies. Measurement of steepest track density gradients indicate that while there are finite differences between spectra exhibited by individual gas-rich meteorites, the average solar flare spectral shapes have been similar over the last ~4 b.y. or so.

Accretion of interplanetary dust and comets by A-type stars is investigated to see whether this process can explain the overabundances of heavy elements in Ap and Am stars. The dust particles spiral in by the Poynting-Robertson effect and evaporate above the star. This process is evaluated by considering the evolution of silicate and graphite particles in the radiation field of Alpha Leo (B7 V). It is found that graphite particles evaporate above 20 stellar radii and silicate dust grains above 50 stellar radii. The evaporated atoms will be quickly ionized. In the case of Am stars the ions will wander off and not reach the photosphere, but in the case of Ap stars they can be trapped by the magnetic field of the star and reach the surface. The magnetosphere of a typical Ap star is modeled, and the fate of the ions is studied. The efficiency of accretion from the magnetosphere is sensitive to the presence of any plasma in the magnetosphere. The comet impact process is found capable of producing the abundance anomalies in Ap as well as Am stars, assuming that the comet impact rate is 0.03/yr, nearly the same as in the solar system.