Theoretical Investigations of Third-Order Dispersion Term on Relative Intensity Noise for Dispersive Optical Communication System

In this article we present improved theoretical investigations into relative intensity noise (RIN), including the impact of a third-order dispersion term for dispervive optical communication systems. It has been shown that the third-order dispersion term has no impact on RIN even at high noise frequencies as reported by other authors, but with second-order dispersion compensation, the RIN can be dramatically reduced, thereby improving overall system performance. Further, the impact of fiber length and laser linewidth has been investigated for RIN. It has been shown that, as the fiber length increases, the value of RIN increases but the improvement over RIN with second-order dispersion compensation decreases. Also, with decrease in the value of linewidth, the RIN can be reduced to a great extent.     

Laser irradiation of AISI 316L stainless steel coated with Si3N4 and Ti

AISI 316L stainless steel was laser surface treated with different compositions of Si₃N₄ and Ti under various laser-processing parameters to improve its surface hardness through reinforcement of Ti-based silicides. The laser-treated regions exhibited improved surface hardness (250–1000 HV), variations in the surface morphology (smooth and bowl like) and presence of cracks and pores depending upon the Si₃N₄–Ti composition and laser-processing parameters. The study shows that when the Si₃N₄–Ti composition is 75–25 wt% and laser parameters are 1.5 kW laser power and 1.0 m min⁻¹ scan speed, a laser-treated region with high hardness of about 800 HV and smooth surface morphology as well as free from pores and cracks is observed. The X-ray diffractometer (XRD) and Energy-Dispersive Spectroscopy (EDS) analyses show that the laser surface-treated region has reinforced phase of Ti₅Si₃ and retained austenitic structure. The reinforced phase gives rise to very high hardness (or wear resistance) and also a corrosion resistance.     

Spider Monkey Optimization algorithm for numerical optimization

Swarm intelligence is one of the most promising area for the researchers in the field of numerical optimization. Researchers have developed many algorithms by simulating the swarming behavior of various creatures like ants, honey bees, fish, birds and the findings are very motivating. In this paper, a new approach for numerical optimization is proposed by modeling the foraging behavior of spider monkeys. Spider monkeys have been categorized as fission–fusion social structure based animals. The animals which follow fission–fusion social systems, split themselves from large to smaller groups and vice-versa based on the scarcity or availability of food. The proposed swarm intelligence approach is named as Spider Monkey Optimization (SMO) algorithm and can broadly be classified as an algorithm inspired by intelligent foraging behavior of fission–fusion social structure based animals.     

Automatic estimation of the first subglottal resonance

This letter focuses on the automatic estimation of the first subglottal resonance (Sg1). A database comprising speech and subglottal data of native American English speakers and bilingual Spanish/English speakers was used for the analysis. Data from 11 speakers (five males and six females) were used to derive an empirical relation among the first formant frequency, fundamental frequency, and Sg1. Using the derived relation, Sg1 was automatically estimated from voiced sounds in English and Spanish sentences spoken by 22 different speakers (11 males and 11 females). The error in estimating Sg1 was less than 50 Hz, on average.     

Polyaniline-Anchored Metal Salts for Michael Reaction of α,β-Unsaturated Ketones

A catalyst consisting of polyaniline-anchored metal salts is used as a Lewis acid to promote the Michael reaction of α,β-unsaturated ketones. The reaction is performed efficiently with imidazole, acetyl acetone, and ethyl acetate as Michel donors and chalcones as the acceptors under ultrasound irradiation.     

Green chemistry-mediated synthesis of nanostructures of afterglow phosphor

Various nanostructures of SrAl₂O₄:Eu²⁺, Dy³⁺ (SAC) afterglow phosphor were prepared in a single-step reaction using a green chemistry-mediated modified combustion process. The evolution of hazardous NxOx gases during the customary combustion reaction was completely eliminated by employing an innovative complex formation route. Another fascinating feature of the process was that, a slight change in the processing conditions ensured the synthesis of either nanoparticles or nanowires. The photoluminescence spectrum of nanophosphor showed a slight blue shift in emission (∼511 nm) as compared to the bulk phosphor (∼520 nm). The afterglow (decay) profiles of SAC nanoparticles, nanowires and bulk phosphor were compared. The chemistry underlying the nanostructure synthesis and the probable afterglow mechanism were discussed.