Using Markov Learning Utilization Model for Resource Allocation in Cloud of Thing Network

Wireless Personal Communications - The integration of the Internet of Things (IoT) and cloud environment has led to the creation of Cloud of Things, which has given rise to new challenges in IoT...     

Additive manufacturing of monolithic supercapacitors with biopolymer separator

Journal of Applied Electrochemistry - In this paper, additive layer-by-layer fabrication of a fully screen printed monolithic supercapacitor exhibiting performance comparable with supercapacitors...     

Removal of melanoidin from molasses spent wash using fly ash-clay adsorbents

Removal of melanoidin pigment from molasses spent wash was investigated using a new adsorbent. Solid adsorbents were fabricated from charcoal fly ash and clay. The effect of various molasses concentration (6 to 12 g/l) on removal efficiency was studied. The obtained results revealed that maximum removal efficiency of 82% was achieved at the molasses concentration of 6 g/l and contact time of 7 h. The saturated porous adsorbents were regenerated and reused to conduct similar experiments. The achieved data showed that more than 90% of the capacity of the fresh adsorbent was recovered after regeneration. Various adsorption isotherms of Langmuir, Freundlich, Temkin and Harkins-Jura were applied to interpret the obtained experimental data. The obtained results revealed that the sorption data were well described by the Harkins-Jura model. Also, various kinetic models of pseudo-first order, pseudo-second order, Elovich and intra-particle diffusion were used to predict the characteristic parameters which are useful in process design. It was concluded that the best fit was obtained with pseudo-second order kinetic model at low molasses concentrations.     

Fabrication and Characterization of Functionally Graded Al/SiCp Composites Produced by Remelting and Sedimentation Process

A new process termed here as remelting and sedimentation (RAS) was developed to produce functionally graded Al/SiC composites with a smooth concentration gradient of SiC particles along the height of samples, as opposed to a step change. For this purpose, first settling velocities of different-sized SiC particles in aluminum A356 melt were measured, and the results exhibited a reasonably good agreement with those predicted via the modified Stokes law. Then slices of particulate Al/SiC composites with different SiC contents of 5, 10, 15, and 20 vol.% were stacked in a cast iron mold and heated at 650 °C resulting in remelting and unification of the different composite parts. Considering the preliminary settling experiments, the composite slurry was held at this temperature for three different times to investigate the optimum holding time for obtaining a smooth gradient of SiC concentration along the height of the sample. After quenching, the samples were sectioned and subjected to metallographic studies and hardness measurements. The results confirmed that holding the melt for 60 s provides sufficient settling and redistribution of SiC particles and results in successful production of a functionally graded material.     

Promethazine determination in plasma samples by using carbon paste electrode modified with molecularly imprinted polymer (MIP): Coupling of extraction, preconcentration and electrochemical determination

A promethazine (PMZ) molecularly imprinted polymer (MIP) and a non-imprinted polymer (NIP) were synthesized by two different formulations of methacrylic acid-ethylene glycol dimethacrylate (MAA-EGDMA) and vinyl benzene-divinyl benzene (VB-DVB). Then, the MIPs were used to modify the carbon paste electrode (CP). The response difference between MIP-CP and NIP-CP electrodes, containing VB-DVB polymer, was higher than that for MIP-CP and NIP-CP modified with polymer of MAA-EGDMA, indicating the lower nonselective surface adsorption property of the VB-DVB based MIP. The MIP, incorporated in the carbon paste electrode, functioned as selectively recognition element and pre-concentrator agent for PMZ determination. The prepared electrode was used for PMZ measurement by the three steps procedure including analyte extraction in the electrode, electrode washing and electrochemical measurement of PMZ. It was shown that the electrode washing, after PMZ extraction, led to enhanced selectivity. Square wave voltammetry (SWV) for PMZ determination by proposed electrode was proved to be better than that of differential pulse voltammetry. Some parameters, effective on the electrode response, were optimized and then a calibration curve was plotted. Two dynamic linear range of 7 × 10⁻⁹ to 4 × 10⁻⁷ and 4 × 10⁻⁷ to 7 × 10⁻⁶ mol L⁻¹ were obtained. The detection limit of the method was calculated equal to 3.2 × 10⁻⁹ mol L⁻¹. This method was used successful for PMZ determination in blood serum sample.     

Polyoxometalate–molybdenylacetylacetonate hybrid complex: A reusable and efficient catalyst for oxidation of alkenes with tert-butylhydroperoxide

The hybrid complex consist of molybdenylacetylacetonate complex covalently linked to a lacunary Keggin-type polyoxometalate, K₈[SiW₁₁O₃₉] (POM), was synthesized and characterized by elemental analysis, SEM, XRD, diffuse reflectance UV–Vis and FT-IR spectroscopic methods. The hybrid complex, [MoO₂(acac)–POM] (1), was used for alkene epoxidation with tert-BuOOH in 1,2-dichloroethane as solvent. The complex (1) can catalyze epoxidation of various olefins including non-activated terminal olefins. The effect of reaction parameters such as oxidant, solvent, and temperature on the epoxidation of cyclooctene was also investigated. This heterogeneous catalyst was reused several times in the oxidation of cyclooctene.     

Developing a Robust Multi-Attribute Decision-Making Framework to Evaluate Performance of Water System Design and Planning under Climate Change

In theory, emergence of robustness concept has pushed decision-makers toward designing alternatives, such as resistant against the potential fluctuations fueled by uncertain surrounding environment. This study promotes an objective-based multi-attributes decision-making framework that takes into account the uncertainties associated with the impacts of the climate change on water resources systems. To capture the uncertainties of climate change, Monte Carlo approach has been used to generate a series of ensembles. These generated ensembles represent the stochastic behavior of the hydro-climatic variables under climate change. This framework represents the inherent uncertainties associated with hydro-climatic simulations. Next, a coupled TOPSIS/Entropy multi-attribute decision-making framework has been formed to prioritize the feasible alternatives using system performance measures. The main objective of this framework is to minimize the risk of deceptive and subjective assessments during decision-making process. Karkheh River basin has been selected as a case study to demonstrate the implication of this framework. Using a set of system performance attributes, the performance of two hydropower systems has been estimated during the baseline period and under the future climate change conditions. According to the conducted frequency analysis, the alternative in which both hydropower projects would go under construction emerged as the robust solution (i.e., there was a 99.9% chance that it outperforms other solutions). The results indicate that the construction of these hydropower systems leads to the increase of Karkheh River basin robustness in the future.

     

Pore-scale modeling of competition and cooperation of multispecies biofilms for nutrients in changing environments

In this article, we developed a pore-scale model of integrated lattice Boltzmann method and cellular automata to investigate competitive growth of aerobic nitrite and ammonium oxidizers in a bioreactor. The results showed that inlet nutrient concentrations have significant effects on maximum biofilm concentration, ratio of microorganisms' concentrations, growth pattern, and time. The local availability of oxygen could control the competition, resulting in different growth patterns. The coexistence of ammonium and nitrite in same inlet zone increased not only the biofilm concentration (7%) but also the ratio of microorganisms' concentrations (36%). Although this coexistence decreased the total biofilm concentration in some cases, it increased the growth rate about 25%. Changes of the maximum biomass concentration could change biofilm concentration of about 40% and microorganisms' concentrations ratio of about 30%. This framework provides a powerful tool to improve our understanding of dynamic interdependency of many complex microbial consortia systems with environments.     

Coupled Quantity-Quality Simulation-Optimization Model for Conjunctive Surface-Groundwater Use

Many water resources optimization problems involve conflicting objectives which the main goal is to find a set of optimal solutions on, or near to, Pareto front. In this study a multi-objective water allocation model was developed for optimization of conjunctive use of surface water and groundwater resources to achieve sustainable supply of agricultural water. Here, the water resource allocation model is based on simulation-optimization (SO) modeling approach. Two surrogate models, namely an Artificial Neural Network model for groundwater level simulation and a Genetic Programming model for TDS concentration prediction were coupled with NSGA-II. The objective functions involved: 1) minimizing water shortage relative to the water demand, 2) minimizing the drawdown of groundwater level, and 3) minimizing the groundwater quality changes. According to the MSE and R² criteria, the results showed that the surrogate models for prediction of groundwater level and TDS concentration performed favorably in comparison to the measured values at the number of observation wells. In Najaf Abad plain case study, the average drawdown was limited to 0.18 m and the average TDS concentration also decreased from 1257 mg/lit to 1229 mg/lit under optimal conditions.     

Investigation of the effect of magnetic field on mass transfer parameters of CO2 absorption using Fe3O4‐water nanofluid

In this study, the enhancement of physical absorption of carbon dioxide by Fe₃O₄‐water nanofluid under the influence of AC and DC magnetic fields was investigated. Furthermore, a gas‐liquid mass transfer model for single bubble systems was applied to predict mass transfer parameters. The coated Fe₃O₄ nanoparticles were prepared using co‐percipitation method. The results from characterization indicated that the nanoparticles surfaces were covered with hydroxyl groups and nanoparticles diameter were 10–13 nm. The findings showed that the mass transfer rate and solubility of carbon dioxide in magnetic nanofluid increased with an increase in the magnetic field strength. Results indicated that the enhancement of carbon dioxide solubility and average molar flux gas into liquid phase, particularly in the case of AC magnetic field. Moreover, results demonstrated that mass diffusivity of CO₂ in nanofluid and renewal surface factor increased when the intensity of the field increased and consequently diffusion layer thickness decreased. © 2016 American Institute of Chemical Engineers AIChE J, 63: 2176–2186, 2017