Predictive model for the frictional characteristics of woven fabrics optimized by the genetic algorithm

Surface friction of fabrics is one of the prominent tactile properties which influence the comfort and application of clothes. In this paper, a new approach is proposed to characterize the surface friction of woven fabrics by presenting a model based on fabric structural parameters. The model coefficients are optimized with the aid of the genetic algorithm, using the experimental friction results obtained from the multi-directional tactile sensing mechanism. The model is developed using the properties of 25 groups of woven fabrics consisting of 5 various weave structures and 5 different weft densities, with similar fibre composition. The statistical analysis of Friction results clarified that the effect of fabric structural parameters such as weave structure and weft density is significant in the confidence range of 95%. The importance of proposing the friction model is that the frictional properties of woven fabrics can be estimated by considering the structural parameters of woven fabrics. This model can be utilized for the forecasting of the friction resistance of various types of woven fabrics without experimental testing procedures.     

The Impact of Climate Change on Hydro-Meteorological Droughts Using Copula Functions

Climate change has made many alterations to the climate of earth, including hydro-climatic extreme events. To investigate the impact of climate change on hydro-meteorological droughts in the Kamal-Saleh dam basin in Markazi province, Iran, proportional to future climate conditions, a new and comprehensive index was developed with the aim of accurately estimating drought in a more realistic condition. This aggregate drought index (ADI) represented the main meteorological and hydrological characteristics of drought. Temperature and precipitation projections for future climates were simulated by five CMIP5 models and downscaled over the study area during 2050s (2040–2069) and 2080s (2070–2099) relative to the baseline period (1976–2005). By fitting five univariate distribution functions on drought severity and duration, proper marginal distributions were selected. The joint distribution of drought severity and duration was chosen from five types of copula functions. The results revealed that in future, severe droughts are expected to frequently occur in a shorter period.

     

Nuclear Magnetic Resonance Spectroscopy: A Versatile Tool for Qualitative and Quantitative Analysis of an Emulsifier Mixture of Soybean Oil

Finding a fast, reliable, and reproducible approach for an accurate analysis of complex lipid mixtures of emulsifiers is crucial for the food and beverages, pharmaceuticals, personal care products, cosmetics, and agrochemicals industries. In the current study, a comprehensive qualitative and quantitative nuclear magnetic resonance (NMR) spectroscopy analysis of a high monoester mixture of soybean oil (HMMS) was conducted using ¹H, ¹³C, and ³¹P NMR of 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane (CTDP) derivatives. The HMMS was produced by enzymatic alcoholysis of soybean oil and 1.2-propanediol in a supercritical CO₂ system. Compositional distribution analysis, quantified by aliphatic carbons with ¹³C NMR, showed that HMMS is composed of more unsaturated fatty acids, comprised of polyunsaturated fatty acids (PUFA) (60 ± 1.1%) and monounsaturated fatty acids (MUFA) (22 ± 0.8%), than saturated fatty acids (18 ± 0.9%). The ³¹P NMR quantification of HMMS demonstrated that, out of the total amount of monoacylglycerols (MAG), they are composed of 21 ± 2.9% of 2-MAG and 4 ± 0.3% of 1-MAG. Among the three techniques, ³¹P NMR spectroscopy proved to be a practical methodology with high reproducibility for the precise detection and quantification of partially esterified glycerols and free fatty acids in complex lipid mixtures.     

A New Method for Flood Routing Utilizing Four-Parameter Nonlinear Muskingum and Shark Algorithm

Water Resources Management - Considering the great importance of flood prediction, flood routing based on Shark Algorithm (SA) and Four-Parameter Nonlinear Muskingum (FPNM) has been proposed in the...     

The analysis of severely deformed pure Fe structure aided by X-ray diffraction profile

Pure Fe was severely deformed by a combination of shaped cold rolling and cold drawing. X-ray diffraction profiles analysis was applied in accordance with the Williamson-Hall (WH) and modified Williamson-Hall (MWH) methods to identify crystallite sizes of the deformed specimens. It was found that some differences exist between the results of WH and MWH procedures using the hkl dependent Young’s modulus or considering the average dislocation contrast factor. The latter method is more accurate and enables the determination of the character of dislocations in plastically deformed Fe. It was shown that by increasing deformation strain, the screw dislocations dominated. The enhancement of hardness occurs in the deformed Fe due to grain refinement, dislocation accumulation and deformation-induced vacancies.     

Acoustic Detection of Phase Transitions at the Nanoscale

Materials near structural phase transitions find applications in a wide range of devices. Typically, phase transitions are determined macroscopically through measurements of relevant order parameters and related property coefficients. Here, a method for understanding electric field induced phase transitions in ferroelectrically active materials at the nanometer scale via acoustic detection with band‐excitation piezoresponse force microscopy (BE‐PFM) is introduced. Specifically, the field‐induced rhombohedral (R) to tetragonal (T) phase transition in single crystal 0.72PbMg_1/3Nb_2/3O₃‐0.28PbTiO₃ (PMN‐PT) is mapped. It is shown that due to sample heterogeneity, some regions are more prone to the R–T transition, and display signatures in the acquired piezoresponse loops, as well as pronounced softening in the elastic modulus (monitored via the resonant frequency and calibrated with models of cantilever dynamics) that occurs just prior to phase switching. Landau–Devonshire thermodynamic theory confirms the stability of the tetragonal phase under applied fields in PMN‐PT, while phase‐field modeling suggests that the transition evolves smoothly in the probed volume of the tip, both in agreement with the BE‐PFM results. These results confirm the validity and utility of utilizing acoustic changes at phase transitions to detect their onset in nanoscale probed volumes, allowing spatial mapping of their onset with unprecedented resolution.     

The role of Pb and annealing temperature on the structural,magnetic, optical and dielectric properties of W-type hexaferrite nanostructures

In this paper, W-type Sr_1-xPb_xCo₂Fe₁₆O₂₇ nanostructures were synthesized by auto-combustion sol-gel method. Then, the effects of annealing temperature and Pb contents on the structural, magnetic, optical, and dielectric properties of Sr_1-xPb_xCo₂Fe₁₆O₂₇ nanostructure were investigated. First, a gel of metal nitrates with a specific molar ratio with x different was prepared and then the gel was annealed at different temperatures for 4?h. To determine the annealing temperature of the samples, the prepared gel was examined by thermogravimetric analysis and differential thermal analysis. The morphology and crystal structure of the prepared samples were characterized by field emission scanning electron microscopy (FESEM) and X-ray diffraction pattern (XRD). The results of XRD patterns indicated that the annealing temperature of synthesized Sr_1-xPb_xCo₂Fe₁₆O₂₇ was reduced by increasing Pb contents. In addition, FESEM images showed that the microstructure of the samples was homogeneous and uniform, but since the samples have a magnetic property, the particles were aggregated. Fourier transform infrared analysis (FT-IR) was used to confirm the phase formation. The FT-IR results of the samples indicated that the tetrahedral and octahedral sites, which are the important attributes of hexaferrites, were formed. The magnetic properties of the samples were measured by vibrating sample magnetometer (VSM). The VSM results of the samples showed that because of increasing Pb content, the amount of saturation magnetization and that of magnetic coercivity decreased from 81.29 to 10.23?emu/g and 2285–477?Oe, respectively. The optical properties of the samples were investigated by ultraviolet–visible spectroscopy, which revealed that the energy gap decreases and the absorption peaks move towards longer wavelengths by increasing Pb content. The dielectric properties of the samples were investigated by the LCR meter. It was found that by increasing frequency, the dielectric constant (ε^′) and the dielectric loss (?) of the samples were decreased.     

Fabrication and characterization of hollow nanofibrous PA6 yarn reinforced with CNTs

Core-sheath nanofibrous yarns were obtained through electrospinning of polyamide 6 (PA6) solution containing different concentrations of multi-wall carbon nanotubes (MWNTs) as sheath and PVA multifilament as the yarn core. By dissolving PVA, for obtaining conductive hollow nanofibrous PA6/MWNTs yarn, two types of porosity could be obtained including hollow central tube due to the structure of hollow yarn and nano-porous areas embedded in electrospun nanofibers. SEM results showed that the diameters of nanofibers were varying in the range of 103–145 nm obeying MWNTs concentrations and TEM results revealed that the MWNTs were embedded in nanofiber matrix as straight and aligned form. DSC analysis showed that electrospinning process caused the formation of less-ordered γ phase in nanofibers. The electrical conductivity of yarns increased from 10^?13 S m^?1 to 2.4?×?10^?6 S m^?1 with increasing the concentration of nanotubes from 0 wt.% to 7 wt.%.     

Nanofiltration membranes based on PA6/EVOH with variable composition and morphology

Nanofiltration PA6/EVOH membranes were prepared through a nonsolvent induced phase separation technique. The effects of polymer concentration in the solution and solvent evaporation time on the performance and morphology of the resulting membranes were investigated by cloud point titration, permeation, and scanning electron microscopy (SEM). Experimental cloud point data for various prepared membranes suggested that polymer solutions with higher concentrations of PA6/EVOH need a less content of nonsolvent. SEM observations show that an increase in polymer concentration leads to formation of a thin dense layer on the surface of the membrane thanks to pore size reduction. However, dense top layer of membrane becomes thicker as polymer concentration increases from 15 wt% to 20 wt%. The performance of membranes reveals a decrease with polymer concentration in casting solution. By contrast, Polyamide/Poly(ethylene‐co‐vinyl alcohol) membranes show an optimal performance with various formic acid evaporation times. J. VINYL ADDIT. TECHNOL., 25:E28–E34, 2019. © 2018 Society of Plastics Engineers     

Experimental and Theoretical Determination of the Antioxidant Properties of Aromatic Monoterpenes of Thymol and 2,5,6-Trifluorothymol

The objective of this research was to conduct an experimental and theoretical investigation into the antioxidant properties of thymol and 2,5,6-trifluorothymol. Calculations based on the density functional theory were performed using the B3LYP exchange-correlation functional and the 6-311G(d,p) standard basis set to determine the carbon-fluorine bond dissociation enthalpy of 2,5,6-trifluorothymol and thymol in the gas phase and in solution in water and in methanol. Computed delta binding dissociation energies and delta ionization potential values of theoretical 2,5,6-trifluorothymol, test of total phenolics, and 1,1-diphenyl-2-picrylhydrazyl assay allowed the authors to conclude that both thymol and 2,5,6-trifluorothymol have a protective antioxidant action.