Simultaneous hydrogen and aromatics enhancement by obtaining optimum temperature profile and hydrogen removal in naphtha reforming process; a novel theoretical study

In this novel theoretical study, the dimensionless length of the conventional naphtha reforming reactor has been discretized into differential segments and three different cases have been investigated in this regard. In the first case, inlet temperature of each segment has been optimized via differential evolution (DE) method to obtain the optimized temperature profile along the reactors by joining the achieved inlet temperatures for each segment on the figure. Same approach has been applied in the second case in order to achieve optimum hydrogen permeation rate. In the third case, the optimum profiles of temperature and hydrogen removal have been obtained using DE optimization technique using the same approach. The objective of each optimization case is to maximize the hydrogen and aromatics production rate. As it is discussed further, unlike previous studies, application of optimum temperature and hydrogen permeation profiles simultaneously boosts hydrogen and aromatics production rate significantly. 10% and 24% enhancement in hydrogen and aromatics production rates can be achieved by applying the novel theoretical concepts in the conventional naphtha reforming process.     

Real-time optical spectrum monitoring in filterless optical metro networks

Photonic Network Communications - A novel method for disaster management using free space optical link is proposed in this paper. Free space optics recently gained great attention since it has...     

Application of Magnetic ordered mesoporous carbon Nanocomposite for the Removal of Ponceau 4R Using Factorial Experimental Design

Silicon - Nanocomposites of ordered mesoporous carbon with silica coated magnetite nanoparticles (Fe3O4@SiO2-CMK-8, MNCs) were synthesized by carbonizing sucrose inside the pores of the Kit-6...     

CO2 biofixation by Synechococcus elongatus from the power plant flue gas under various light–dark cycles

Clean Technologies and Environmental Policy - Carbon dioxide emission, which acts as one of the major agents of greenhouse gases (GHG), has significant effects on global warming. Nowadays, there is...     

Response surface methodology for optimizing the induction conditions of recombinant interferon beta during high cell density culture

A human interferon beta expressed from a synthetic gene was produced in high cell density culture by recombinant Escherichia coli using an optimized linear feeding strategy. The optimal induction conditions to be determined consisted of inducer concentration and dry cell weight at the time of induction. For this purpose, the response surface methodology was applied. Under optimal conditions, the maximum interferon beta concentration and overall productivity of 2.2 g/l and 0.151 g/l h were obtained, respectively, as the highest amounts ever reported for this protein. Two optimal ranges of dry cell weight and IPTG concentration consisting of 50 g/l and 2.54 mM, and 70 g/l and 1.29 mM were predicted, respectively, at which maximum productivity was achieved. By using a novel feeding strategy with linear variation of specific growth rate during high cell density fermentation, the maximum biomass productivity of 5.037 g/l h was obtained in a defined medium during 16 h. Then, by applying the optimum induction conditions, we accomplished an increase in overall productivity by more than three-fold over the central point. This is the first report showing the high production of human interferon beta by a synthetic gene in a simple fed-batch high cell density culture of recombinant E. coli in a defined medium.     

Membrane bioreactor for treatment of pharmaceutical wastewater containing acetaminophen

Treatment of pharmaceutical wastewater is a real challenge for wastewater engineers. In this study, a pilot-scale system including an external loop airlift membrane bioreactor (ELAMBR) was applied for treatment of a synthetic pharmaceutical wastewater. The performance of this system was evaluated in removal of acetaminophen as the main pollutant of a pharmaceutical wastewater. A conventional activated sludge (CAS process) laboratory system was used in parallel with this system to compare both systems in regard to their ability for acetaminophen removal. The performance of the ELAMBR system was monitored for approximately one month to investigate the long-term operational stability of the system and possible effects of solids retention time on the efficiency of removal of acetaminophen. The removal efficiency was significantly higher in the ELAMBR system than the CAS process. 100% of the acetaminophen was removed after 2 days in this system. The results also showed that initial concentration of acetaminophen, chemical oxygen demand (COD) and mixed liquid suspended solids (MLSS) are the most effective parameters in removal of a pollutant such as acetaminophen. This study demonstrates the usefulness of ELAMBR system for pharmaceutical wastewater treatment with the advantages such as: (i) simple operation and maintenance, (ii) efficient removal of pharmaceutical pollutant and COD and (iii) low-energy consumption.     

Development and implementation of neural network observers to estimate synchronous generators’ dynamic parameters using on-line operating data

This paper illustrates a new application of artificial neural network (ANN) observers in identifying and estimating synchronous generator dynamic parameters via time-domain, on-line disturbance measurements. To prepare the training database for an ANN observer, the transient behaviours of synchronous generators have been determined through off-line simulations of a generator operating in a one-machine-infinite-bus environment. The Levenberg–Marquardt optimization utilising very fast back propagation algorithm has been adopted for training feed-forward neural networks. The inputs of ANNs are organized in coordination with the data from the observability analysis of synchronous generator parameters in its dynamic behaviour. A collection of ANNs with same inputs but different outputs is developed to determine a set of the parameters. The ANNs are utilized to estimate the above parameters by the measurements for every kind of fault separately. The robustness tests are executed by on-line measurements to identify the parameters. Simulation studies not only indicate that the observer is capable to identify the dynamic parameters of synchronous generator but also show that the tests which have given better results in identification of each dynamic parameter can be acquired.     

Effect of defects and loading on prediction of Young��s modulus of SWCNTs

In this paper, the influence of various vacancy and Stone-Wales defects on the Young??s modulus of single-walled carbon nanotubes is investigated via a structural model. Dispersion in experimental results is the motivation for this work. Our results show that the type of method used (loading and boundary condition) for the prediction of the Young??s modulus of SWCNTs is very important for the results. The effect of different types of defects on the Young??s modulus is also studied for zigzag and armchair nanotubes with various aspect ratios (length/diameter). A comparison of our results with those of experimental methods indicates that for the exact prediction of the Young??s modulus of SWCNTs we need to apply the correct conditions.     

Kinetic Study of the Reduction Step for Chemical Looping Steam Methane Reforming by CeO2-Fe2O3 Oxygen Carriers

The reduction stage of chemical looping steam methane reforming was investigated to determine the kinetics of the reduction reaction for CeO₂-Fe₂O₃ mixed oxides. CeO₂, Fe₂O₃, and CeO₂-Fe₂O₃ mixed oxides with different molar ratios were prepared by chemical precipitation. Characterization tests indicated the lowest Brunauer-Emmett-Teller surface area for samples with higher Fe content. The largest area under reduction peaks during hydrogen temperature-programmed reduction measurements was also related to the samples with highest Fe content. Reduction of the oxygen carriers with lower Fe content was well represented by a phase boundary-controlled model.