Swelling properties of CMC‐g‐poly (AAm‐co‐AMPS) superabsorbent hydrogel

A series of biopolymer‐based superabsorbent hydrogels based on carboxymethyl cellulose has been prepared by free‐radical graft copolymerization of acrylamide and 2‐acrylamido‐2‐methylpropan sulfonic acid (AMPS) in aqueous solution using methylenebisacrylamide as a crosslinking agent and ammonium persulfate as an initiator. The effect of variables on the swelling capacity such as: acrylamide/AMPS weight ratio, reaction temperature, and concentration of the initiator and crosslinker were systematically optimized. The results indicated that with increasing the amount of AMPS, the swelling capacity is increased. FT‐IR spectroscopy and scanning electron microscope analysis were used to confirm the hydrogel structure. Swelling measurements of the synthesized hydrogels in different salt solutions indicated considerable swelling capacity. The absorbency under load of the superabsorbent hydrogels was determined by using an absorbency under load tester at various applied pressures. A preliminary swelling and deswelling behaviors of the hydrogels were also studied. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

H2 production in silica membrane reactor via methanol steam reforming: Modeling and HAZOP analysis

The main aim of this work is the presentation of both qualitative safety and quantitative operating analyses of silica membrane reactor (MR) for carrying out methanol steam reforming (MSR) reaction to produce hydrogen. To perform the safety analysis, HAZOP method is used. Before the HAZOP analysis, a comprehensive investigation of most important operating parameters effects on silica MR performance is required. Therefore, for a quantitative analysis, a 1-dimensional and isothermal model is developed for evaluating the reaction temperature, reaction pressure, feed molar ratio (steam/methanol) and feed flow rate effects on silica MR performance in terms of methanol conversion and hydrogen recovery. The model validation results show good agreement with experimental data from literature. As a consequence, simulation results indicate that the reaction pressure and feed molar ratio have dual effect on silica MR performance. In particular, it is found that methanol conversion is decreased by increasing the reaction pressure from 1.5 to 4.0 bar, whereas over 4.0 bar, it is improved. Moreover, the hydrogen recovery is decreased by increasing the feed molar ratio from 1 to 5, while over 5, it was approximately constant. After the evaluation of modeling results, the HAZOP analysis for silica MR is carried out during MSR reaction. The analysed operating parameters in the modeling study have been considered as key parameters in the HAZOP analysis. The safety assessment results are presented in tables as check list. By considering the HAZOP results, safety pretreatment works are recommended before or during the experimental tests of MSR reaction in silica MR. According to different parameters consequences, reaction temperature is the most critical parameter in MSR reaction for the silica MR studied in this work. In particular, to avoid the consequences of temperature deviation, it is recommended to use a PID temperature controller in the silica MR for MSR reaction.     

Optima localization by vehicle formations imitating the Nelder-Mead simplex algorithm

In this paper, we address the problem of localizing extrema points and iso-contours of ambient environmental fields (specifically, ocean bottom landscape and underwater plumes) using a networked formation of autonomous underwater vehicles. We propose the use of the Nelder-Mead extension to the basic simplex nonlinear optimization algorithm. In these robust gradient-free strategies, decisions are solely made based on field values measured by the individual vehicles, while measurements are fused and actions decided according to the algorithm. A main goal of this paper is to trigger interest in direct search methods as pertains to this type of robotic problem.     

Developing an Interactive Spatial Multi-Attribute Decision Support System for Assessing Water Resources Allocation Scenarios

Water Resources Management - In water resource management, assessing water resource allocation scenarios (WRASs) is an important multi-attribute decision making (MADM) problem. It involves...     

A Case Study on Optimization of Biomass Flow During Single-Screw Extrusion Cooking Using Genetic Algorithm (GA) and Response Surface Method (RSM)

In the present study, response surface method (RSM) and genetic algorithm (GA) were used to study the effects of process variables like screw speed, rpm (x ₁), L/D ratio (x ₂), barrel temperature (°C; x ₃), and feed mix moisture content (%; x ₄), on flow rate of biomass during single-screw extrusion cooking. A second-order regression equation was developed for flow rate in terms of the process variables. The significance of the process variables based on Pareto chart indicated that screw speed and feed mix moisture content had the most influence followed by L/D ratio and barrel temperature on the flow rate. RSM analysis indicated that a screw speed?>?80 rpm, L/D ratio?>?12, barrel temperature?>?80 °C, and feed mix moisture content?>?20% resulted in maximum flow rate. Increase in screw speed and L/D ratio increased the drag flow and also the path of traverse of the feed mix inside the extruder resulting in more shear. The presence of lipids of about 35% in the biomass feed mix might have induced a lubrication effect and has significantly influenced the flow rate. The second-order regression equations were further used as the objective function for optimization using genetic algorithm. A population of 100 and iterations of 100 have successfully led to convergence the optimum. The maximum and minimum flow rates obtained using GA were 13.19?×?10^?7 m³/s (x ₁?=?139.08 rpm, x ₂?=?15.90, x ₃?=?99.56 °C, and x ₄?=?59.72%) and 0.53?×?10^?7 m³/s (x ₁?=?59.65 rpm, x ₂?=?11.93, x ₃?=?68.98 °C, and x ₄?=?20.04%).     

Mechanical characterization of graphene oxide reinforced epoxy at different strain rates

Strain rate has significant effect on mechanical behavior of the thermoset polymers. The rate sensitivity is more complicated for thermoset nanocomposites, which compose of two quite different types of materials. Nanofiller‐reinforced epoxy resin is widely used in the industry. In the present work, epoxy resin is reinforced by 0.05 to 0.7 wt% nanographene oxide (GO). The strain rate sensitivity of the fabricated nanocomposites is investigated through compressive test carried out at the strain rates of 0.001–1,900 s^?1. The stress–strain curves of the nanocomposites indicated considerable difference between the low‐strain and high‐strain‐rate responses of the specimens. The results showed that the compressive strength of the nanocomposites was improved by more than 100% at high strain rates with respect to the low strain rates. Also, the addition of nano‐GO had influence on compressive strength enhancement but not as significant as the effect of strain rate. It was observed that the effect of GO was less important for higher strain rates. The experimental compressive strength and modulus of elasticity of the nanocomposites were casted in empirical relations for low and high strain rates for various filler weight percentages. Scanning electron microscopy was also used to examine the quality of GO dispersion. POLYM. ENG. SCI., 59:1636–1647 2019. © 2019 Society of Plastics Engineers