New formulation for compressive strength of CFRP confined concrete cylinders using linear genetic programming

This paper proposes a new approach for the formulation of compressive strength of carbon fiber reinforced plastic (CFRP) confined concrete cylinders using a promising variant of genetic programming (GP) namely, linear genetic programming (LGP). The LGP-based models are constructed using two different sets of input data. The first set of inputs comprises diameter of concrete cylinder, unconfined concrete strength, tensile strength of CFRP laminate and total thickness of utilized CFRP layers. The second set includes unconfined concrete strength and ultimate confinement pressure which are the most widely used parameters in the CFRP confinement existing models. The models are developed based on experimental results collected from the available literature. The results demonstrate that the LGP-based formulas are able to predict the ultimate compressive strength of concrete cylinders with an acceptable level of accuracy. The LGP results are also compared with several CFRP confinement models presented in the literature and found to be more accurate in nearly all of the cases. Moreover, the formulas evolved by LGP are quite short and simple and seem to be practical for use. A subsequent parametric study is also carried out and the trends of the results have been confirmed via some previous laboratory studies.     

Novel approach to the synthesis of core-shell particles by sacrificial polymer shell method

In this work a new approach has been developed for the synthesis of SiO₂@Y₂O₃ particles with core-shell structure. The method is based on the synthesis of a covalently bonded sacrificial polymer shell grown onto silica particles. It is suitable to promote and stabilize the adsorption of different ions, namely Yttrium from its nitrate solution. After calcination and consequent elimination of the sacrificial polymer shell, the SiO₂@Y₂O₃ core-shell particles are obtained. Results reveal that the shell thickness of these core-shell particles is higher and more uniform than that of particles prepared without sacrificial polymer shell.     

Producing of AA5083/ZrO2 Nanocomposite by Friction Stir Processing (FSP)

In this study, friction stir processing (FSP) was used to produce AA5083/ZrO₂ nanocomposite layer. Optical microscopy and SEM were used to probe the microstructures formed in the composite layer. In addition, the mechanical properties of each sample are characterized using both tensile and hardness tests. Results showed that FSP is an effective process to fabricate AA5083/ZrO₂ nanocomposite layer with uniform distribution of ZrO₂ particles, good interfacial integrity, and significant grain refinement. On processing, in the proper combination of process parameters, the metal matrix composite layer was observed to have increased tensile and hardness properties.     

Influence of electrodeposition potential,TiO2 nanoparticles and chromium (III) inhibitor addition on the corrosion protection performance of organosilane coating on aluminium

In this work, the anticorrosion properties of phenyl trimethoxysilane (PTMS) films coated on aluminium 5000 series alloys were studied. PTMS films were deposited at various cathodic potentials. The optimum electrodeposition potential was found to be ?0.8?V vs. SCE. The coatings were also modified by different amounts of nano-TiO₂. In order to introduce corrosion inhibition and a self-repair property of the PTMS film, the addition of chromium (III) corrosion inhibitor in the presence of nano-TiO₂ was studied. The anticorrosion performance of coatings was investigated in a 3.5 wt.% NaCl solution. At optimum deposition potential, the ‘critical’ nano-TiO₂ and Cr(III) contents were both observed, under which the obtained PTMS coatings show the highest anticorrosion performance. The surface morphologies of PTMS coatings were examined by scanning electron microscopy. The results showed that the coatings deposited at ?0.8?V vs. SCE, from 20?ppm of nano-TiO₂ and 0.003 M Cr(III) inhibitor present uniform and compact morphologies.     

Influence of carbohydrate source and buffer on rumen fermentation characteristics, milk yield, and milk composition in early-lactation Holstein cows

The effects of concentrate to forage ratio and sodium bicarbonate (buffer) supplementation on intake, ruminal fermentation characteristics, digestibility coefficients, milk yield, and milk composition were examined in 4 cannulated Holstein cows (100 +/- 20 d in milk). A 4 x 4 Latin square design with 2 x 2 factorial arrangement of treatments was implemented for 3-wk experimental periods. The 4 treatments were a 50:50 concentrate to forage ratio with 1.2% of dry matter (DM) and without added buffer and a 75:25 concentrate to forage ratio with (1.2% of DM) and without (0% of DM) buffer. The forage component of the ration was a 50:50 mixture of alfalfa and barley and triticale silage, and diets were fed ad libitum as a total mixed ration. Although feed intake was not influenced by treatments, substantial treatment differences were observed for milk yield and milk composition. Cows fed high-concentrate diet had lower ruminal pH, ruminal acetate, and butyrate concentrations, whereas propionate concentrations were significantly elevated. The addition of buffer, at both levels of concentrate inclusion, resulted in elevated total volatile fatty acids and acetate concentrations. We concluded that altering the forage concentrate ratio in the diet of lactation cows influenced milk yield and milk composition, but the addition of buffer to the diet prevented the elevation in trans-C18:1 fatty acids in milk fat, and related milk fat depression, associated with feeding high-concentrate diets.     

Sequential Microwave-Ultrasound-Assisted Extraction for Isolation of Piperine from Black Pepper (<Emphasis Type="Italic">Piper nigrum</Emphasis> L.)

Piperine is the natural bioactive component of black pepper (Piper nigrum L.) with several astounding therapeutic properties. In this study, sequential microwave-ultrasound-assisted extraction approach was used for isolation of piperine from black pepper. The effect of various factors such as extraction solvent, particle size of pepper, solvent to solid ratio, microwave power and time and ultrasound temperature and time on the extraction yield of piperine was considered. The maximum extraction yield was 46.6 mg piperine/g pepper which was obtained using ethanol as solvent at the particle size of 0.15 mm, solvent to solid ratio of 20:1, microwave power of 100 W for 1 min, and ultrasound temperature of 50 ^° C for 30 min. This extraction yield was higher than those obtained by Soxhlet (39.1 mg/g), microwave-assisted (38.8 mg/g) and ultrasound-assisted (37.0 mg/g) extractions. The purity of the extracted piperine was 81.4% as determined by HPLC analysis. The FTIR and UV-vis analyses confirmed that the structure of piperine remained intact after extraction and purification which is very important for medicinal applications.     

Phasor measurement unit based transmission line protection scheme design

This paper presents an adaptive transmission line protection scheme based on synchronized phasor measurement units. This scheme uses the positive-sequence voltage and current phasors at both ends of a transmission line to determine the parameter of the transmission line and the location of a fault on the transmission line. This scheme can be used for the protection of both single- and double-circuit transmission lines. This scheme is also robust against power swing conditions. A novel adaptive single pole auto re-closer is introduced based on the proposed scheme due to its capability of differentiating transient and permanent faults. System simulation studies show that the proposed scheme is able to operate fast and accurately for transmission line protection.     

Photocrosslinking of styrene–isoprene–styrene; effect of benzoin and ethylene glycol dimethacrylate on physical properties

Crosslinking reaction of polymer by ultraviolet (UV) irradiation has been important in industries. In this work, photocrosslinking of styrene–isoprene–styrene (SIS) triblock copolymer in the presence of benzoin photoinitiator and a dimethacrylate monomer as crosslinking agent was investigated. Curing of samples was initiated under UV irradiation. Benzoin was used as photoinitiator because it contains chromophore group that could absorb UV irradiation. Ethylene glycol dimethacrylate (EGDMA) was used as crosslinking agent, since it has alkene functional groups that could react with the alkene group of SIS. ATR-FTIR spectra of samples show that absorption band of double bond at 1500–1600?cm^?1 decreases after UV exposure. Increasing the concentration of benzoin (0.1–1?phr) and EGDMA (1–10?phr) leads to an increase in gel content and hardness, while swelling ratio decreases. After 5?min heating at 150?°C, about 20%wt of the unirradiated compound became insoluble, because heating of compound at 150?°C causes crosslinking reaction without any irradiation.     

Synthesis of mullite nanofibres by electrospinning of solutions containing different proportions of polyvinyl butyral

In this paper, the synthesis of continuous mullite (3Al₂O₃·2SiO₂) nanofibres by combination of the sol–gel and electrospinning technique is reported. To find out the optimum viscosity of the electrospinning solution for obtaining the high quality mullite nanofibers, solutions containing different amounts of polyvinyl butyral (PVB, 0–8 wt%) and the precursor sol were prepared for the electrospinning process. The precursor sol was made by using proper amounts of aluminium isopropoxide (AIP), hydrated aluminium nitrate (AN) and tetraethylorthosilicate (TEOS). Crystal phase, microstructure and thermal decomposition behaviour of the electrospun mullite nanofibres were investigated by conventional methods of analysis. The optimal amount of PVB in the electrospinning polymeric solutions was found to be between 4 and 6 wt% and the mullite nanofibres obtained as such were pure, smooth and uniform with diameter sizes of 85–130 nm after calcination at 1200 °C.     

The adsorption of malachite green (MG) as a cationic dye onto functionalized multi walled carbon nanotubes

Synthetic dyes are widely used by several industries to color their products. The discharge of colored wastewater into the hydrosphere causes serious environmental problems. We used functionalized multi wall carbon nanotubes as an adsorbent for the adsorption of cationic dye, malachite green, from aqueous solution. Based on information provided by the Iranian Research Institute of Petroleum Industry, carbon nanotubes are produced using a chemical vapor deposition (CVD) technique. These as-received MWCNTs were functionalized by acid treatment. The remaining dye concentration was read by UV-visible absorption spectroscopy at maximum adsorption wavelength. The effect of different operational parameters such as contact time, pH of solution, adsorbent dose and initial dye concentration were studied. The results showed that by increasing of contact time, pH and adsorbent dose the removal of dye increased, but by increasing initial dye concentration, the removal efficiency decreased. Adsorption isotherms and kinetics behavior of f-MWCNTs for removal of malachite green was analyzed, and fitted to various existing models. The experimental data were well correlated with the Langmuir isotherm with a maximum adsorption capacity (q _m ) and regression coefficient (R²) of 142.85 mg/g and 0.997, respectively. The results of this study indicate that functionalized multi wall carbon nanotubes can be used as an effective adsorbent for the removal of dyes.