Recycled Polyolefin-Based Plastic Wastes for Sound Absorption

Recycling of high-volume polyolefin-based packaging wastes in India is challenging, as they have low recycle value, high levels of contamination, and lack of direct processing methods. This work discusses a two-stage mechanical processing method for recycling the polyolefin-based plastic wastes that are not conventionally recycled. With the objective of improving specific properties like sound absorption and noise reduction, inhomogeneities were introduced in the recycled product. This was achieved by mixing polyolefin-based packaging wastes with other waste materials such as plastic-coated aluminium foils, expanded polystyrene, and coir pith in varying quantities. More than 30 times volume reduction was achieved by a two-stage compression molding process. The sound absorption properties of the recycled materials are found to be comparable to expanded polystyrene and glass wool when small quantities (2–3 wt%) of materials like expanded polystyrene waste and coir pith were added. Impact strength of the recycled material decreased with increasing amounts of secondary additives like metal foils. Flexural strength of the recycled material was found to be maximum at about 30 wt% of metal foils. The end product could find applications in the construction industry due to the sound-absorption properties and the mechanical strength.     

KY0.58Gd0.22Lu0.17Tm0.03(WO4)2 buried rib waveguide lasers

CW mirrorless laser operation at 1840 nm at room temperature was observed in buried rib waveguides of KY_0.58Gd_0.22Lu_0.17Tm_0.03(WO₄)₂ fabricated by structuring KY(WO₄) substrates by Ar-ion milling and subsequent liquid phase epitaxial growth of the active layer on these substrates. Laser efficiency and laser threshold seems to change with the width of the channels fabricated.     

Experimental study of diethyl ether addition on the performance and emissions of a diesel engine

Recently investigations were carried out on the utilisation of light fraction pyrolysis oil (LFPO) in diesel engine, which was obtained from a tyre recycling plant. The 40LFPO blend, which comprised 40% LFPO and 60% diesel composition gave better performance and lower emissions than the blends containing 20LFPO, 60LFPO and 80LFPO. The ignition delays of the blends were longer than that of diesel fuel, because of their lower cetane numbers. The aim of this investigation was to study effect the adding small quantities of Diethyl ether (DEE) whose cetane number is 125, to 40LFPO on the engine behaviour in terms of performance parameters and exhaust emissions. The percentage of DEE was varied from 1% to 4% in steps of 1% on a volume basis. The results of the performance and emission parameters of the engine run on the 40LFPO-DEE blends were evaluated, compared with the diesel operation of the same engine and presented in this article.     

Optimization of weld bead geometry in plasma transferred arc hardfaced austenitic stainless steel plates using genetic algorithm

Plasma transferred arc hardfacing has attracted increasing attention for its effective protection against corrosion, thermal shock, and abrasion. The quality of hardfaced components depends on the weld bead geometry and dilution, which have to be properly controlled and optimized to ensure better economy and desirable mechanical characteristics of the weld. These objectives can be fulfilled by developing mathematical equations to predict the dimensions of the weld bead. This paper highlights the development of such mathematical equations using multiple regression analysis, correlating various process parameters to weld bead geometry in PTA hardfacing of Colmonoy 5, a nickel-based alloy over stainless steel 316 L plates. The experiments were conducted based on a five factor, five level central composite rotatable design matrix. A genetic algorithm (GA) was developed to optimize the process parameters for achieving the desired bead geometry variables.     

Cooperative lattice coding and decoding in half-duplex channels

We propose novel lattice coding/decoding schemes for half-duplex outage-limited cooperative channels. These schemes are inspired by the cooperation protocols of Azarian et al. and enjoy an excellent performance-complexity tradeoff. More specifically, for the. relay channel, we first use our lattice coding framework to generalize Yang and Belfiore implementation of the non-orthogonal amplify and forward cooperation protocol. This generalization is shown to offer significant performance gains while keeping the decoding complexity manageable. We then devise a novel variant of the dynamic decode and forward protocol, along with a lattice-coded implementation, which enjoys a near-optimal diversity-multiplexing tradeoff with a low encoding/decoding complexity. Finally, for the cooperative multiple-access channel, we present a lattice-coded implementation of the non-orthogonal amplify and forward protocol and demonstrate its excellent performance-complexity tradeoff. Throughout the paper, we establish the performance gains of our proposed protocols via a comprehensive simulation study     

Domain structure studies on Pb(Zn1/3Nb2/3)O3–PbTiO3 mixed crystal system

In this investigation, ferroelectric Pb(Zn_1/3Nb_2/3)O₃–PbTiO₃ single crystals have been grown by modified flux technique with PbO self flux. Well-defined domain patterns were observed through polarized light on the as-grown crystals. Fingerprint like pattern and tweed pattern have also been observed. In PZN–PT system the fingerprint domain area is found to be elongated along one direction for increasing PT content.     

Preparation of nanocrystalline Mg4Nb2O9 by citrate gel method

A gel was formed when a aqueous solution of Mg(NO₃)₂, NbF₅ and citric acid in stoichiometric ratio was heated on a water bath. No precipitation was observed at acidic pH and gellation was complete with evaporation of the solvent. This gel on decomposition at 750°C produced nanocrystallites of ternary oxide, Mg₄Nb₂O₉ (M4N2). The phase contents and lattice parameters were studied by powder X-ray diffraction (XRD) at various temperatures. Particle size and morphology were studied by transmission electron spectroscopy (TEM). For comparison, M4N2 powders were also prepared by conventional ceramic route at 900°C.