Extraction of Fe(III) from phosphoric acid by HDDNSA

A study was conducted on the stoichiometry of the reaction that takes place on the extraction of ferric ions by didodecyl naphthalene sulphonic acid (HDDNSA) from phosphoric acid solutions. The experimental results were numerically analyzed by nonlinear regression. It was found that ferric forms two compounds with HDDNSA, namely Fe(DDNSA)₃, and FeHPO₄-DDNSA. The values of the equilibrium constants of the reactions involved were also calculated.     

Analysis and test procedures for NOR flash memory defects

Widespread use of non-volatile memories, especially flash memories, in diverse applications such as in mobile computing and system-on-chip is becoming a common place. As a result, testing them for faults and reliability is drawing considerable interest of designers and researchers. One of the most predominant failure modes for which these memories must be tested is called disturb faults. In this paper, we first analyze different defects that are responsible for disturb faults using a 2-dimension device simulator. We determine the impact of various defects on cell performance and develop a methodology based on channel erase technique to detect these defects. Our tests are efficient and can be converted to march tests prevalently used to test memories. We also propose a very low cost design-for-testability approach that can be used to apply the test technique developed in this paper.     

Mathematical model evaluating for degradation of azo dye in contaminated water by UV/persulfate process

In the present study, the photooxidative degradation of Acid Red 14 (AR 14) was investigated in the UV/persulfate process, and the results of the degradation rate of AR 14 were parametrically represented by ordinary differential equations to find mathematical model for the degradation rate of AR 14 in this process. Our experimental observations led to a model for AR 14 degradation in the UV/persulfate system that could be used to predict removal efficiency by changes of S₂O₈²⁻ (X₁) and dye concentration (X₂), pH (X₃), temperature (X₄) and also distance of UV lamp from solution (X₅). It was found that persulfate and dye concentrations were the most important parameters for AR 14 degradation rate. Moreover, the results showed that the degradation rate was in good agreement with the first-order kinetics for all the parameter values studied. Moreover, the results of the mathematical model agree well with the experimental values (R² = 0.96). Our findings in this study showed that degradation efficiency of UV/S₂O₈²⁻ process for AR 14 was obtained as 98%. Therefore, this model could be applicable before scaling up the AR 14 degradation using UV/persulfate process.     

The preparation of an amino acid-based surfactant and its potential application as an EOR agent

Most of the synthetic surfactants investigated with the aim of enhanced chemically oil recovery in the literature have environmental drawbacks. In this work, application of an environmentally-friendly synthetic surfactant as an enhanced oil recovery agent is introduced by measuring interfacial tension of water–kerosene systems and wettability alteration of carbonate pellets. For this purpose, an amino acid-based surfactant was initially synthesized using a new synthetic approach which was subsequently confirmed by spectra of Fourier transform infrared and Proton nuclear magnetic resonance. Results showed a value of critical micelle concentration in the range of 9000–9100 ppm for this surfactant. Results also demonstrated a decrease of 38.53% in water–kerosene system interfacial tension and a 17.76% reduction in oil-wetness of the carbonate pellets.     

Kinetic modeling of pyrolysis of three Iranian waste oils in a micro-fluidized bed

Different approaches have been used to convert the waste materials into a clean syngas or other chemicals such as methanol. Among them, pyrolysis is a good candidate to produce the synthesis gas and volatile matters for industrial and refinery applications. In this work, we studied the kinetic and chemical behavior of three Iranian waste oils through a kinetic model and an experimental study. The experiments carried out in a micro-FB reactor, which is a good option for low emissions. Results showed that the reaction temperature and reaction rate are two of the most important factors for maximum conversion level of fuel. Results also showed an optimum value for reaction rate. The modeling results validated against the experimental measurements and found to be in good agreements.     

Correlation of H2S solubility in aqueous MDEA solutions using electrolyte-modified Peng-Robinson plus association equation of state

In this survey, we use the emPR-CPA equation of state to model a ternary system of H₂S solubility in MDEA aqueous solution at different solution compositions, temperatures, pressures, and acid gas loadings. For electrolyte part of the model, MSA theory and the Born term were used. There were 302 experimental data used in this work. To model a ternary system, at first pure components, then binary subsystems, and finally ternary system were modeled using a reactive bubble point pressure calculation method. An overall absolute average deviation percentage equal to 20.85 was achieved so that show the model efficiency for correlation of such systems.     

Modeling of CO2-brine interfacial tension: Application to enhanced oil recovery

Development of reliable and accurate models to estimate carbon dioxide–brine interfacial tension (IFT) is necessary, since its experimental measurement is time-consuming and requires expensive experimental apparatus as well as complicated interpretation procedure. In the current study, feed forward artificial neural network is used for estimation of CO₂–brine IFT based on data from published literature which consists of a number of carbon dioxide–brine interfacial tension data covering broad ranges of temperature, total salinity, mole fractions of impure components and pressure. Trial-and-error method is utilized to optimize the artificial neural network topology in order to enhance its capability of generalization. The results showed that there is good agreement between experimental values and modeling results. Comparison of the empirical correlations with the proposed model suggests that the current model can predict the CO₂–brine IFT more accurately and robustly.     

Electroosmotic micropump for lab‐on‐a‐chip biomedical applications

Lab‐on‐a‐chip (LOC) integrated microfluidics has been a powerful tool for new developments in analytical chemistry. These microfluidic systems enable the miniaturization, integration and automation of complex biochemical assays through the reduction of reagent use and enabling portability. Electroosmotic micropumps could be employed as powerful tools to generate required flow in point of care (POC) devices. In the present study, parallel electroosmotic micropumps are investigated to improve the efficiency of simple micropumps. According to the results, parallel micropumps generate higher flow rate in comparison with conventional electroosmotic pump. In the last decade, a large variety of non‐Newtonian fluids have been utilized in biomedical application but requirements for a POC device such as high efficient driving flow, miniaturization and simple handling of POC devices remain unmet. As a consequence, in this study, power law model as non‐Newtonian fluids that flow through the parallel micropumps are investigated in order to enhance fluid pumping and decreasing voltage requirement.. It is found that as the power law index increases the mass flow rate decreases. Also, the flow rate is almost constant for the higher power law index. Obtained results, demonstrated that parallel micropump could enhance pumping of non‐Newtonian fluid (blood) up to 30%. Copyright © 2016 John Wiley & Sons, Ltd.     

3D FEM analysis,dynamic modeling,and performance assessment of transverse flux PMSG for small‐scale gearless wind energy conversion systems

The transverse flux permanent magnet synchronous generator has a great potential for use in direct‐drive wind energy conversion systems due to its large pole numbers, high torque, and power density. This research work develops dynamic model of a single‐side transverse flux permanent magnet synchronous generator for use in a small‐scale gearless wind energy conversion system. For acquiring the parameters of the considered generator, required for dynamic modeling, 3D finite element model of the machine is developed and analyzed in both magneto‐static and transient modes. Field‐oriented control approach is employed for tracking maximum power point from the variable wind speed. The simulation results illustrate an accurate response of the system to the wind speed variation and proper performance of the developed dynamic model and control approach of the system. Copyright © 2015 John Wiley & Sons, Ltd.     

Mechanical, rheological, and thermal behavior assessments in HDPE/PA-6/EVOH ternary blends with variable morphology

Visco-elastic and dielectric spectra of multiwalled carbon-nanotube reinforced silicon elastomer nanocomposites were used to study relaxation behavior. SEM photomicrographs shows well dispersion of MWCNT in elastomer matrix. In visco-elastic analysis primary relaxation was studied as a function of temperature (?100 to 100 °C) at frequency 1Hz and strain 1 %. The effect of MWCNT loadings on storage modulus, loss modulus, and loss tangent has been studied. The non-linearity in loss tangent, storage modulus and loss modulus was explained on the basis of MWCNT-elastomer interaction and the inter-aggregate attraction of MWCNT. The secondary β relaxation was studied using dielectric relaxation spectra in the frequency range of 0.1 Hz to 10⁶ Hz. The effect of MWCNT loadings on the complex and real parts of impedance was distinctly visible which has been explained on the basis of interfacial polarization of fillers in a heterogeneous medium and relaxation dynamics of polymer chains in the vicinity of fillers. The dielectric formalism has been utilized to further investigate the conductivity and relaxation phenomenon. The ‘percolation limit’ of the MWCNT in the silicon elastomer was found to be in the range of 4 phr loading.