Improvement of the prediction performance of a soft sensor model based on support vector regression for production of ultra-low sulfur diesel

A novel data-driven, soft sensor based on support vector regression(SVR) integrated with a data compression technique was developed to predict the product quality for the hydrodesulfurization(HDS) process. A wide range of experimental data was taken from a HDS setup to train and test the SVR model. Hyper-parameter tuning is one of the main challenges to improve predictive accuracy of the SVR model.Therefore, a hybrid approach using a combination of genetic algorithm(GA) and sequential quadratic programming(SQP)methods(GA–SQP) was developed. Performance of different optimization algorithms including GA–SQP, GA, pattern search(PS), and grid search(GS) indicated that the best average absolute relative error(AARE), squared correlation coefficient(R2), and computation time(CT)(AARE = 0.0745, R2= 0.997 and CT = 56 s) was accomplished by the hybrid algorithm. Moreover, to reduce the CT and improve the accuracy of the SVR model, the vector quantization(VQ) technique was used. The results also showed that the VQ technique can decrease the training time and improve prediction performance of the SVR model. The proposed method can provide a robust, soft sensor in a wide range of sulfur contents with good accuracy.     

Valproic Acid as a Potential Inhibitor of Plasmodium falciparum Histone Deacetylase 1 (PfHDAC1): An in Silico Approach

A new Plasmodium falciparum histone deacetylase1 (PfHDAC1) homology model was built based on the highest sequence identity available template human histone deacetylase 2 structure. The generated model was carefully evaluated for stereochemical accuracy, folding correctness and overall structure quality. All evaluations were acceptable and consistent. Docking a group of hydroxamic acid histone deacetylase inhibitors and valproic acid has shown binding poses that agree well with inhibitor-bound histone deacetylase-solved structural interactions. Docking affinity dG scores were in agreement with available experimental binding affinities. Further, enzyme-ligand complex stability and reliability were investigated by running 5-nanosecond molecular dynamics simulations. Thorough analysis of the simulation trajectories has shown that enzyme-ligand complexes were stable during the simulation period. Interestingly, the calculated theoretical binding energies of the docked hydroxamic acid inhibitors have shown that the model can discriminate between strong and weaker inhibitors and agrees well with the experimental affinities reported in the literature. The model and the docking methodology can be used in screening virtual libraries for PfHDAC1 inhibitors, since the docking scores have ranked ligands in accordance with experimental binding affinities. Valproic acid calculated theoretical binding energy suggests that it may inhibit PfHDAC1.     

Effect of borax on the thermal and mechanical properties of ethylene‐propylene‐diene terpolymer rubber‐based heat insulator

The effect of Borax on the mechanical and ablation properties of three different ethylene‐propylene‐diene terpolymer (EPDM) compounds containing 20 phr carbon fiber, 20 phr Kevlar or 10 phr/ 10 phr carbon fiber/ Kevlar was investigated. All formulations contained 30 phr fumed silica powder and 10 phr paraffinic oil. It was found that adding Borax to the composite samples containing carbon fiber or Kevlar fiber or their mixture with an equal ratio can increase the tensile strength, elastic modulus and hardness with a slightly decrease in the elongation at break of the rubber samples. The results of thermogravimetry analysis (TGA) on the various samples showed significant increase in the char yield at 670°C by adding Borax to the rubber compounds. Moreover, ablation resistance of samples was also improved by increasing Borax content. Meanwhile, density and thermal conductivity of the insulator were also reduced up to about 10% when the carbon fiber was replaced with the Borax. The results indicated that composites containing Kevlar have high storage modulus and produce compact and stable char. EPDM rubber composite containing Borax (20 phr), carbon fiber (10 phr), and Kevlar (10 phr) showed thermal and ablative properties comparable with those of the asbestos‐ filled EPDM. The thermal conductivity and ablation rate of the above‐ mentioned sample were 0.287 W/m/K and 0.13 mm/s respectively. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41936.     

Rabi oscillation generation in the microring resonator system with double-series ring resonators

In this paper, a microring resonator (MRR) system using double-series ring resonators is proposed to generate and investigate the Rabi oscillations. The system is made up of silicon-on-insulator and attached to bus waveguide which is used as propagation and oscillation medium. The scattering matrix method is employed to determine the output signal intensity which acts as the input source between two-level Rabi oscillation states, where the increase of Rabi oscillation frequency with time is obtained at the resonant state. The population probability of the excited state is higher and unstable at the optical resonant state due to the nonlinear spontaneous emission process. The enhanced spontaneous emission can be managed by the atom (photon) excitation, which can be useful for atomic related sensors and single-photon source applications.     

A simple method for preparation of polymer microcellular foams by in situ generation of supercritical carbon dioxide from dry ice

In this work, poly(methyl methacrylate) (PMMA) and PMMA/nanoclay nanocomposite microcellular foams were successfully prepared using a simple method based on in situ generation of supercritical carbon dioxide (CO₂) from dry ice. The method was compared with conventional methods exempted from high pressure pump and a separate CO₂ tank. Effect of various processing conditions such as saturation temperature and pressure and clay concentration on cellular morphology and hardness of the prepared microcellular foams was examined. State of the clay dispersion in the prepared PMMA/clay nanocomposites was characterized using X-ray diffraction and transmission electron microscopy techniques. Field emission scanning electron microscopy was used to study cellular morphology of the prepared foams. It was observed that elevation of saturation temperature from 85 to 105 °C at constant saturation pressure increased cell density and decreased average cell size of the prepared PMMA foams. Furthermore, an increase in saturation pressure from 120 to 180 bar resulted in a reduction in average cell diameter and an increase in cell density of the prepared PMMA foams. On the basis of the gathered results, optimum conditions for preparation of PMMA microcellular foams were determined and applied for preparation of PMMA/nanoclay microcellular foams. It was shown that incorporation of clay into the polymer matrix resulted in a finer and more uniform cellular morphology in the final microcellular foams. It was also observed that incorporation of nanoclay into the prepared foams, up to 3 wt%, led to a moderate increase in the foam hardness.     

The effect of carbon black and HALS hybrid systems on the UV stability of high-density polyethylene (HDPE)

In the present study, attempts were made to study the effect of a hybrid UV stabilizing system on high-density polyethylene (HDPE). For this purpose, high molecular weight PE was used to prepare samples containing different amounts of hindered amine light stabilizer (HALS), carbon black (CB) and HALS/CB systems as UV stabilizers. All samples were exposed to UV irradiation simulating 4 and 8 years of exposure to solar irradiation in central part of Iran (Yazd). FTIR results were used to estimate the carbonyl index (CI) of the samples. It showed that CI increased as UV exposure time increased. However, it was found out that in the samples having both stabilizers (HALS/CB), CI value was much less compared to other samples indicating that the presence of hybrid system would show a synergism effect on UV stabilization of HDPE. The gel content of all samples was measured and it confirmed the same results. The PECH sample (containing HALS and CB) showed the least gel content after equivalent time of 4 and 8 years of exposure (2 and 3.5 wt%, respectively) which was in accordance with CI result. Furthermore, the effect of different UV stabilizing systems on the mechanical properties of HDPE was studied. For this purpose, elastic modulus, elongation-at-break and yield stress of the samples were measured. It was found out that HALS/CB hybrid system preserved the mechanical properties of HDPE much better than the other systems, which was attributed to the synergistic effect of the simultaneous use of HALS and CB.     

Recording duration of ambient vibration monitoring for system identification of tall telecommunication towers

It is necessary to have reliable field measurement records for estimation of dynamic characteristics. Increasing duration of the record is one of the common methods for reduction of such errors in the results. Dynamic characteristics of telecommunication towers in higher modes are important for designers, but these parameters could be obtained from ambient vibration monitoring during typhoons in which duration of vibration is not long enough for reducing measurement errors. This paper suggests a procedure for obtaining the duration of recording time for more reliable determination of structural characteristics of telecommunication towers. It is suggested to record the vibration of towers in the form of a set of long‐term and short‐term duration recordings for lower and higher modes, respectively. This procedure was verified with field measurement of Milad telecommunication tower. The results show that natural frequencies determined by this procedure are in good agreement with finite element model analysis. Copyright © 2013 John Wiley & Sons, Ltd.     

PSO-ANFIS modeling of viscosity for mixtures of Athabasca bitumen and a high-boiling n-alkane

The bitumen and heavy oil reservoirs are more in number than light crude oil reservoirs in the world. To increase the empty space between molecules and decrease viscosity, the bitumen was diluted with a liquid solvent such as tetradecane. Due to the sensitivity of enhanced oil recovery process, the accurate approximation for the viscosity of mentioned mixture is important. The purpose of this study was to develop an effective relation between the viscosity of Athabasca bitumen and heavy n-alkane mixtures based on pressure, temperature, and the weight percentage of n-tetradecane using the adaptive neuro-fuzzy inference system method. For this model, the value of MRE and R² was obtained as 0.34% and 1.00, respectively; so this model can be applied as an accurate approximation for any mixture of heavy oil with a liquid solvent.     

Characterization of uncertainty (probabilistic models) in verification of unreinforced masonry shear wall / Charakterisierung der Unschärfe (probabilistische Modelle) beim Nachweis von Wandscheiben aus unbewehrtem Mauerwerk

The model uncertainty has significant role in determination of safety factor. Eurocode has been considered partial factor covering uncertainties in the resistance model. Moreover, the model uncertainty has important role in full probabilistic verification. A stochastic analysis may yield to realistic results, only if the uncertainties have been involved in the calculation, properly. The uncertainty in predicted load‐carrying model may be identified by comparing the observed (experimental records) load‐carrying behaviour with the predicted value. Some general recommendations for considering uncertainty in probabilistic verifications are available in literature. In this study, the deviation of predicted values according to DIN EN 1996‐1‐1/NA model of masonry shear wall from test results has been derived. The best‐fitted distribution with associated statistical parameters (type of distribution, mean and coefficient of variation) has been proposed for uncertainty model. The uncertainty models have been compared with recommendations in the literature.