An inertia-adaptive particle swarm system with particle mobility factor for improved global optimization

Particle Swarm Optimization (PSO) has recently emerged as a nature-inspired algorithm for real parameter optimization. This article describes a method for improving the final accuracy and the convergence speed of PSO by firstly adding a new coefficient (called mobility factor) to the position updating equation and secondly modulating the inertia weight according to the distance between a particle and the globally best position found so far. The two-fold modification tries to balance between the explorative and exploitative tendencies of the swarm with an objective of achieving better search performance. We also mathematically analyze the effect of the modifications on the dynamics of the PSO algorithm. The new algorithm has been shown to be statistically significantly better than the basic PSO and four of its state-of-the-art variants on a twelve-function test-suite in terms of speed, accuracy, and robustness.     

Polyacrylonitrile solution homogeneity study by dynamic shear rheology and the effect on the carbon fiber tensile strength

Poly(acrylonitrile‐co‐methacrylic acid) (PAN‐co‐MAA)/N,N‐dimethylformamide (DMF) solutions were prepared and dynamic shear rheology of these solutions were investigated. With increasing stirring time up to 72 h at 70°C, the polymer solution became less elastic (more liquid‐like) with a ～60% reduction in the zero‐shear viscosity. Relaxation spectra of the PAN‐co‐MAA/DMF solutions yield a decrease in relaxation time (disentanglement time, τ_d), corresponding to an about 8% decrease in viscosity average molecular weight. The log‐log plot of G′ (storage modulus) versus G″ (loss modulus) exhibited an increase in slope as a function of stirring time, suggesting that the molecular level solution homogeneity increased. In order to study the effect of solution homogeneity on the resulting carbon fiber tensile strength, multiple PAN‐co‐MAA/DMF solutions were prepared, and the precursor fibers were processed using gel‐spinning, followed by continuous stabilization and carbonization. The rheological properties of each solution were also measured and correlated with the tensile strength values of the carbon fibers. It was observed that with increasing the slope of the G′ versus G″ log‐log plot from 1.471 to 1.552, and reducing interfilament fiber friction during precursor fiber drawing through the addition of a fiber washing step prior to fiber drawing, the carbon fiber strength was improved (from 3.7 to 5.8 GPa). This suggests that along with precursor fiber manufacturing and carbonization, the solution homogeneity is also very important to obtain high strength carbon fiber. POLYM. ENG. SCI., 56:361–370, 2016. © 2016 Society of Plastics Engineers     

Soluble‐eggshell‐membrane‐protein‐modified porous silk fibroin scaffolds with enhanced cell adhesion and proliferation properties

In this study, a porous silk fibroin (SF) scaffold was modified with soluble eggshell membrane protein (SEP) with the aim of improving the cell affinity properties of the scaffold for tissue regeneration. The pore size and porosity of the prepared scaffold were in the ranges 200–300 μm and 85–90%, respectively. The existence of SEP on the scaffold surface and the structural and thermal stability were confirmed by energy‐dispersive X‐ray spectroscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. The cell culture study indicated a significant improvement in the cell adhesion and proliferation of mesenchymal stem cells (MSCs) on the SF scaffold modified with SEP. The cytocompatibility of the SEP‐conjugated SF scaffold was confirmed by a 3‐(4,5‐dimethyltriazol‐2‐y1)‐2,5‐diphenyl tetrazolium assay. Thus, this study demonstrated that the biomimic properties of the scaffold could be enhanced by surface modification with SEP. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40138.     

Impacts of conservation agriculture on soil aggregation and aggregate-associated N under an irrigated agroecosystem of the Indo-Gangetic Plains

We evaluated impacts of conservation agriculture (zero tillage, bed planting and residue retention) on changes in total soil N (TSN) and aggregate-associated N storage in a sandy loam soil of the Indo-Gangetic Plains. Cotton (Gossypium hirsutum) and wheat (Triticum aestivum) crops were grown during the first 3 years (2008–2011) and in the last year, maize (Zea mays) and wheat were cultivated. Results indicate that after 4 years the plots under zero tillage with bed planting (ZT-B) and zero tillage with flat planting (ZT-F) had 15 % higher TSN concentrations than conventional tillage and bed planting plots (CT-B) (0.63 g kg^?1 soil) in the 0–5 cm soil layer. CT-B plots had lower soil bulk density that ZT plots in that layer. Plots under ZT-B (0.57 Mg ha^?1) contained 20 % higher TSN stock in the 0–5 cm soil layer than CT-B plots (0.48 Mg ha^?1). However, tillage had no impact on TSN concentration or stock in the sub-surface (5–15 and 15–30 cm) soil layers. Thus, in the 0–30 cm soil layer, ZT-B plots contained 6 and 5 % higher (P > 0.05) TSN stock compared with CT-B (2.15 Mg N ha^?1) and CT-F (2.19 Mg N ha^?1) plots respectively after 4 years. Plots that received cotton/maize + wheat residue (C/M + W RES) contained 16 % higher TSN concentration than plots with residues removed (N RES; 0.62 g kg^?1 soil) in the surface (0–5 cm) layer. Plots with only cotton/maize residue (C/M RES) or only wheat residue (W RES) retention/incorporation had similar TSN concentrations and stocks in the subsurface layer. Plots under ZT-B also had more macroaggregates (0.25–8 mm) and greater mean weight diameter with lower silt + clay sized particles than CT-B plots in that layer. A greater proportion of large macroaggregates (2–8 mm) in the plots under C/M + W RES compared with N RES were observed. In the 5–15 cm soil layer ZT-B and C/M + W RES treated plots had more macroaggregates and greater mean weight diameter than CT-B and N RES treated plots, respectively. Because of the greater amount of large aggregates, plots under ZT-B and C/M + W RES had 49 and 35 % higher large macroaggregate-associated N stocks than CT-B (38 kg TSN ha^?1) and N RES (40 kg TSN ha^?1) plots, respectively, in the 0–5 cm soil layer, although aggregates had similar TSN concentrations in all plots. Both tillage and residue retention had greater effects on aggregate-associated N stocks in the 5–15 cm layers. In addition to N content within large macroaggregates, small macroaggregate-associated N contents were also positively affected by ZT-B and C/M + W RES. Tillage and residue retention interaction effects were not significant for all parameters. Thus, the adoption of ZT in permanent beds with crop residue addition is a better management option for improvement of soil N (and thus possibly a reduced dose of fertilizer N can be adopted in the long run), as the management practice has the potential to improve soil aggregation with greater accumulation of TSN within macroaggregates, and this trend would likely have additive effects with advancing years of the same management practices in this region.     

Modification of nylon 66 by electron beam irradiation for improved properties and superior performances

Nylon 66 has been transformed into a material with significantly improved properties like hardness, tensile strength, and flexural modulus by processing it under the optimized dose rate of electron beam in the presence of suitable crosslinkers. Furthermore, percent water absorption of nylon 66 was reduced substantially on irradiation. Thermogravimetric analysis revealed that thermal stability of nylon 66 improved with increasing dose of radiation. Improvement of mechanical and thermal properties and reduction of water absorption of nylon 66 were due to the crosslinking of polyamide molecules made possible by the high energy radiation. Increase of crosslinking with increasing radiation dose was verified by the increase of gel content at higher doses. Differential scanning calorimetry showed that both melting and crystallization temperatures along with percent crystallinity of nylon 66 were decreased with the increasing dose of radiation leading to the development of more amorphous character in this semicrystalline polymer. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Chemical synthesis of nanocrystalline lead zirconate-titanate powders using tartarate precursor

Nanocrystalline (30 nm) lead zirconate-titanate (PZT) ceramics, with Zr/Ti ratio 60:40, was prepared by a chemical method starting from a mixed metal ion–tartarate (Zr⁴⁺, Ti⁴⁺)–EDTA (Pb²⁺) complex solution. After complete evaporation of the mixed complex solution, a fluffy dried mass, known as precursor material was obtained. Heat-treatments of the precursor material at 400°C/2 h resulting single phase PZT. The precursor and heat-treated powders were characterized by TG/DTA, XRD and TEM analysis. The result shows that the process provides a technically simple route for the preparation of nanocrystalline PZT powders at low preparation temperatures.     

Synthesis of spodumene and spodumene — zirconia composite powders using aqueous sol-gel method

Pure spodumene and spodumene-zirconia (5, 10, 15 mol%) composite powders were prepared using aqueous sol-gel method employing lithium formate, aluminium formate, zirconium formate and tetraethoxy silane (TEOS) as starting materials in aqueous medium. The gels prepared by this method were dried at 100°C for 24h and then calcined for 2h at different temperatures ranging from 500°C to 800°C. X-ray powder diffraction (XRD), differential thermal analysis (DTA), thermogravimetric analysis (TGA) and infra-red spectroscopy analysis (IR) were utilized to characterize the gel powders and calcined powders. Transmission electron microscope (TEM) was used to measure the average particle size of the calcined powders.