A robust genetic algorithm for scheduling realistic hybrid flexible flow line problems

This article addresses the problem of hybrid flexible flow line where some constraints are considered to alleviate the chasm between the real-world industries scheduling and the production scheduling theories. Sequence-dependent setup times, machine release date and time lags are three constraints deemed to project the circumstances commonly found in real-world industries. To tackle the complexity of the problem at hand, we propose an approach base on genetic algorithm (GA). However, the performance of most evolutionary algorithms is significantly impressed by the values determined for the miscellaneous parameters which these algorithms possess. Hence, response surface methodology is applied to set the parameters of GA and to estimate the proper values of GA parameters in continually intervals. Finally, problems of various sizes are utilized to test the performance of the proposed algorithm and to compare it with some existing heuristic in the literature such as SPT, LPT and NEH.     

Comparisons of several variants of continuous quantum-inspired evolutionary algorithms

Abstract

In this study, an extensive numerical analysis is carried out to investigate the effects of different quantum-based operators on the performance of continuous quantum-inspired evolutionary algorithms (QEAs). In this context, different variants of quantum-inspired evolutionary operators are adopted for numerical simulations. Furthermore, some novel chaos-enhanced QEAs are proposed and their performances are evaluated through the numerical comparative study. Based on evaluating the accuracy, robustness, convergence, scalability and sensitivity to initialisation of the rival methods, it is indicated that the algorithmic structure of QEAs is prone to being combined with chaotic maps. The results demonstrate that chaotically implemented QEAs can effectively explore/exploit the solution spaces of different landscapes and dimensionality, and finally, converge to acceptable regions within the solution domain.     

Rotational regimes of freely suspended liquid crystal films under electric current in presence of an external electric field

The electrohydrodynamic (EHD) vortices produced by an electric current in freely suspended liquid crystal (LC) films of N-(4-methoxybenzylidene)-4-butylaniline (MBBA), convert to a pure rotation in the presence of external electric field ( $\it{E}_{{\rm ext}}$ ) perpendicular to the current direction. Here, the direction and strength of the rotation are precisely under control by our self-made device called ??liquid-film motor??. In this paper, we present experimental observations of the EHD fluid flow when external electric field varies from zero to a value in which pure rotation on the liquid crystal (LC) film is observed. We also show experimentally that the presence of external electric field causes a great decrease in the current produced by the voltage V _J required for observing EHD vortices in freely suspended films of MBBA. The LC films begin to rotate when E _ext V _J reaches a threshold value. This threshold is investigated experimentally as a function of voltage V _J and the external electrical field $\it{E}_{{\rm ext}}$ .     

Double‐Sided Surface Passivation of 3D Perovskite Film for High‐Efficiency Mixed‐Dimensional Perovskite Solar Cells

Defect‐mediated carrier recombination at the interfaces between perovskite and neighboring charge transport layers limits the efficiency of most state‐of‐the‐art perovskite solar cells. Passivation of interfacial defects is thus essential for attaining cell efficiencies close to the theoretical limit. In this work, a novel double‐sided passivation of 3D perovskite films is demonstrated with thin surface layers of bulky organic cation–based halide compound forming 2D layered perovskite. Highly efficient (22.77%) mixed‐dimensional perovskite devices with a remarkable open‐circuit voltage of 1.2 V are reported for a perovskite film having an optical bandgap of ≈1.6 eV. Using a combination of experimental and numerical analyses, it is shown that the double‐sided surface layers provide effective defect passivation at both the electron and hole transport layer interfaces, suppressing surface recombination on both sides of the active layer. Despite the semi‐insulating nature of the passivation layers, an increase in the fill factor of optimized cells is observed. The efficient carrier extraction is explained by incomplete surface coverage of the 2D perovskite layer, allowing charge transport through localized unpassivated regions, similar to tunnel‐oxide passivation layers used in silicon photovoltaics. Optimization of the defect passivation properties of these films has the potential to further increase cell efficiencies.     

Effect of processing conditions on the microencapsulation of 1-methylimidazole curing agent using solid epoxy resins

Among various methods for preparation of the non-reactive or latent curing agents for epoxy resins, encapsulation offers a promising and cost-effective method. This system has been used in one-part thermosetting adhesives or prepregs for developing advanced composite materials. In this study, 1-methylimidazole (1-MI) was microencapsulated using solid epoxy resins via solvent evaporation method. The effect of various types of shell materials or solid epoxy resins, different core-to-shell ratios of 30/70, 50/50, and 70/30, and a variety of mixing rates (500, 1000, and 1500 rpm) on the preparation of microcapsules were evaluated. The 1-MI content and microencapsulation efficiency were calculated using thermal gravimetric analysis (TGA). The shape and surface morphology of the prepared microcapsules were evaluated using scanning electron microscopy (SEM) technique. Gel time of the microcapsules mixed with liquid epoxy resin was also investigated. Results showed that by decreasing the core-to-shell ratio at different stirring rates, the encapsulation efficiency increased. The microencapsulation efficiency of 34.8% was obtained at shell-to-core (1-MI) ratio of 70/30 at stirring rate of 500 rpm. The results also showed that at higher mixing rates, 1-MI content in microcapsules was controlled by high shearing force. It has been found that the gel time of the epoxy resin/microcapsule samples was proportional to the imidazole content and it was in agreement with the data obtained by TGA analysis, as well.     

Thermal behavior and electrical conductivity of ethylene vinyl acetate copolymer/expanded graphite nanocomposites: Effects of nanofiller size and loading

Nanocomposites based on ethylene‐vinyl acetate (EVA) copolymer and expanded graphite (EG) were prepared using direct and two‐step melt‐mixing processes. The effect of elongational flow on the dispersion of EG nanoparticles in the polymeric matrix was investigated by thermal analysis and electrical conductivity measurements. Two types of EG having different aspect ratio were applied to prepare the nanocomposites. The nanocomposites containing higher aspect ratio nanofiller have shown higher values of transition temperature (Tg) and a stronger reinforcing effect of EG. The evaluation of EVA crystallization behavior has clarified that both the EG loading and particle size have noticeably influenced the crystallization characteristics of EVA. The restrictions imposed by nanoparticles on molecular motion and, correspondingly, the crystal growth stage have been the most notable effect of EG nanopartciles on the EVA crystallization behavior. Moreover, the presence of EG nanofiller has intensified the formation of a second‐type of EVA crystals during long annealing time. Furthermore, chemically crosslinking of EVA chains has led to the formation of smaller crystals with more uniform size. J. VINYL ADDIT. TECHNOL., 22:51–60, 2016. © 2014 Society of Plastics Engineers     

High-Temperature Superconductivity in Hydrides: Experimental Evidence and Details

Journal of Superconductivity and Novel Magnetism - Since the discovery of superconductivity at?~?200 K in H3S [1], similar or higher transition temperatures, Tcs, have been...     

Effect of Iron Particles Size on the High-Frequency Magnetic Properties of Iron-Borosilicate Soft Magnetic Composites

Iron-borosilicate magnetic composites could be applied as a soft magnetic material in high temperature and high frequency applications. In this research, the magnetic properties of soft magnetic composites with different iron particle sizes made by spark plasma sintering have been investigated. Different magnetic properties such as permeability, loss factor, and quality factor were examined up to frequencies in the order of kilohertz. The microstructural observations indicated the distribution of borosilicate on the iron grain boundaries. The results revealed that the loss factor is smaller for composites with fine particles at high frequencies. In addition, the magnetic impedance for smaller particles was greater. It was also found that the permeability and quality factor of composites with coarse particles are larger than those of fine particles. Indeed, when the particles become coarse, the density of porosities and consequently, the demagnetizing fields decrease which result in the increase of permeability. Furthermore, when the size of particles reduces, the density of grain boundaries enhances which is the main reason of lower loss factor achieved in the composites with fine particles.     

New polyamides based on 2,5‐bis[(4‐carboxyanilino) carbonyl] pyridine and aromatic diamines: Synthesis and characterization

Seven new polyamides 6a–g were synthesized through the direct polycondensation reaction of 2,5‐bis[(4‐carboxyanilino) carbonyl] pyridine 4 with seven derivatives of aromatic diamines 5a–g in a medium consisting of N‐methyl‐2‐pyrrolidone, triphenyl phosphite, calcium chloride, and pyridine. The polycondensation reaction produced a series of novel polyamides containing pyridyl moiety in the main chain in high yield with inherent viscosities between 0.32 – 0.72 dL/g. The resulted polymers were fully characterized by means of FTIR spectroscopy, elemental analyses, inherent viscosity, and solubility tests. Thermal properties of these polymers were investigated by using thermal gravimetric analysis and differential thermal gravimetric. All the polymers were soluble at room temperature in polar solvents, such as N,N‐dimethyl acetamide, N,N‐dimethyl formamide, dimethyl sulfoxide, and N‐methyl‐2‐pyrrolidone. 2,5‐Bis[(4‐carboxyanilino) carbonyl] pyridine 4 as a new monomer containing pyridyl moiety was synthesized by using a two‐step reaction. At first 2,5‐pyridine dicarboxylic acid 1 was converted to 2,5‐pyridine dicarbonyl dichloride 2 . Then diacid 4 was prepared by condensation reaction of diacid chloride 2 with p‐aminobenzoic acid 3. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Parallel image encryption with bitplane decomposition and genetic algorithm

Multimedia Tools and Applications - Image encryption is an efficient technique to protect image content from unauthorized parties. In this paper a parallel image encryption method based on bitplane...