Effects of a proper feature selection on prediction and optimization of drilling rate using intelligent techniques

Engineering with Computers - One of the important factors during drilling times is the rate of penetration (ROP), which is controlled based on different variables. Factors affecting different...     

Mesoporous silica supports for improved thermal stability in supported Au catalysts

In this work, we present a comprehensive review of our research on the role of mesoporous silica pore architecture, composition of the pore walls (addition of Co or Al), and silica surface chemistry (surface modification by TiO₂) to improve the hydrothermal stability of Au particles. We have found that mesoporous silica architecture plays an important role in improving Au stability, with three dimensional mesoporous architectures being less effective than one dimensional (1-D) pores. The tortuous 1-D pores in aerosol silica were found to be most effective at controlling Au particle size. Since Au particles continue to grow larger than the pore diameter, we conclude that Ostwald ripening must be the dominant sintering pathway for these Au catalysts. These catalysts are active for CO oxidation even after the Au particles have grown large enough to block the pores, suggesting that the thin walls of mesoporous silica provide easy access to gas phase molecules. Further improvements in Au stability and reactivity were obtained by surface modification of the aerosol and MCM-41 silica with TiO₂. After TiO₂ modification of the silica, the Au particles remained smaller than the pore size (< 3 nm) even after three cycles of CO oxidation at temperatures up to 400 °C.     

Transesterification of karanja (Pongamia pinnata) oil by solid basic catalysts

The transesterification of karanja oil with methanol was carried out using solid basic catalysts. Alkali metal‐impregnated calcium oxide catalysts, due to their strong basicity, catalyze the transesterification of triacylglycerols. The alkali metal (Li, Na, K)‐doped calcium oxide catalysts were prepared and used for the transesterification of karanja oil containing 0.48–5.75% of free fatty acids (FFA). The reaction conditions, such as catalyst concentration, reaction temperature and molar ratio of methanol/oil, were optimized with the solid basic Li/CaO catalyst. This catalyst, at a concentration of 2 wt‐%, resulted in 94.9 wt‐% of methyl esters in 8 h at a reaction temperature of 65 °C and a 12 : 1 molar ratio of methanol to oil, during methanolysis of karanja oil having 1.45% FFA. The yield of methyl esters decreased from 94.9 to 90.3 wt‐% when the FFA content of karanja oil was increased from 0.48 to 5.75%. The performance of this catalyst was not significantly affected in the presence of a high FFA content up to 5.75%. The catalytic activities of Na/CaO and K/CaO were also studied at the optimized reaction conditions. In these two cases, the reaction initially proceeds slowly, however, leading to similar yields as in the case of Li/CaO after 8 h of reaction time. The purified karanja methyl esters have an acid value of 0.36 mg KOH/g and an ester content of 98.6 wt‐%, which satisfy the American as well as the European specifications for biodiesel in terms of acid value and ester content.     

Dyeing of cotton fabric for improved mosquito repellency

Recently, mosquito repellent textile materials are increasingly in demand from consumers as a preventive measure from mosquito-borne diseases like malaria, dengue. Mosquito repellent-treated textile material initially shows good repellency against mosquitoes but upon repeated washing cycles this effect gets washed off considerably. In the present work, 4-Amino-N, N-diethyl–3-methyl benzamide (MD) is synthesized from N, N-diethyl-m-toluamide (DEET) and it is used as base material for synthesis of azo group. This synthesized base MD was then coupled with three different napthols to get dyed cotton fabric using diazotization process. This dyed cotton fabric has imparted mosquito repellent finish in one, single operation of dyeing cum finishing. This approach is based on modification of universally used mosquito repellent and synthesizing an azo group-based dye in the fibre matrix of the cotton fabric. The chemical structures of the MD were characterized using FT-IR and ¹H-NMR spectroscopy. The fastness properties of the dyed cum finished fabric were measured to evaluate the performance of the dyed fabric. Efficacy of mosquito repellency of the dyed cotton fabric was studied using standard methods. The dyed cotton fabric using napthols and MD showed very good and durable mosquito-repellent activity.     

Synthesis of reactive dye to impart mosquito repellency to nylon

Mosquito repellent textile materials are being increasingly in demand as a preventive measure to protect the consumers from mosquito-borne diseases like malaria, dengue, etc. Many of these agents are applied in post-colouration operation to the fabric. Although initially they show good repellency against mosquitoes, upon repeated washing cycles, this effect gets diminished considerably. In the present work, nylon fabric is imparted mosquito repellent finish in one, single operation of dyeing cum finishing. This approach is based on the modification of commonly used mosquito-repellent N,N-diethyl-m-toluamide (DEET) and synthesizing a reactive dye based on this important ingredient. A reactive dye was synthesized in order to impart mosquito repellency to the nylon 6 fabric, DEET was first subjected to nitration using Potassium nitrate and dichloromethane (DCM). This nitrated product was reduced in the presence of water: ethanol (30:70) and the amine, thus, produced was then condensed with 2, 4, 6-trichloro-1, 3, 5-triazine (cyanuric chloride) a reactive group. The resultant product was finally reacted with an amino group present in 6-Amino-2-naphthalenesulphonic acid (Bronner’s acid) to obtain Sodium6-((4-(diethylcarbamoyl)-2-methylphenyl) amino)-1, 3, 5-triazin-2-yl) amino) naphthalene-2-sulfonate (reactive dye). This reactive dye was then applied on nylon 6 fabric by covalent bonding to provide mosquito-repellent material. The chemical structures of the dye were characterized using FTIR and ¹H-NMR spectroscopy. The melting point of the dye was characterized by Differential Scanning Calorimetry. The fastness properties of the dyed cum finished fabric were measured to evaluate the performance of the dye. Efficacy of mosquito repellency of the treated nylon 6 fabric was studied using standard methods. The nylon 6 fabric reacted with the mosquito-repellent dye and showed very good durable mosquito-repellent activity.     

Kinetics of the formation of symmetrical wax esters from the corresponding alcohols with the use of hydrobromic acid and hydrogen peroxide

The primary aliphatic alcohols n-octanol, n-decanol, and n-dodecanol have been converted to their corresponding symmetrical esters by using HBr and H₂O₂ in the absence of a solvent. The reaction was carried out at 30, 40, and 50°C and at mole ratios of alcohol to HBr of 1∶0.1, 1∶0.2, 1∶0.3, and 1∶0.5. The rate of the reaction was found to increase with increase in the reaction temperature and concentration of HBr. The maximal conversion of n-octanol was 72% at 40°C and a mole ratio of n-octanol to HBr of 1∶0.5. The kinetics of the reaction have been established, and the reaction was found to be first-order with respect to alcohol and bromine concentration in the organic phase, and second-order with respect to both. The second-order rate constants for n-octanol, n-decanol, and n-dodecanol are 27.08, 32.58, and 37.42 mL mol⁻¹ min⁻¹, respectively, at 40°C. The activation energy for the esterification reaction of n-octanol was found to be 16.32 kcal mol⁻¹.     

Heat transfer characteristics of synthetic jet impingement cooling

Synthetic jet is a novel flow technique which synthesizes stagnant air to form a jet, and is potentially useful for cooling applications. The impingement heat transfer characteristics of a synthetic jet are studied in this work. Toward that end, the behavior of the average heat transfer coefficient of the impinged heated surface with variation in the axial distance between the jet and the heated surface is measured. In addition, radial distribution of mean and rms velocity and static pressure are also measured. The experiments are conducted for a wide range of input parameters: the Reynolds number (Re) is in the range of 1500–4200, the ratio of the axial distance between the heated surface and the jet to the jet orifice diameter is in the range of 0–25, and the length of the orifice plate to the orifice diameter varies between 8 and 22 in this study. The maximum heat transfer coefficient with the synthetic jet is found to be upto 11 times more than the heat transfer coefficient for natural convection. The behavior of average Nusselt number is found to be similar to that obtained for a continuous jet. The exponent of maximum Nusselt number with Re varies between 0.6 and 1.4 in the present experiments, depending on the size of the enclosure. A direct comparison with a continuous jet is also made and their performances are found to be comparable under similar set of conditions. Such detailed heat transfer results with a synthetic jet have not been reported earlier and are expected to be useful for cooling of electronics and other devices.     

Specific heat and thermal conductivity of softwood bark and softwood char particles

Very few data exist regarding the thermal properties of softwood bark and therein derived softwood chars. This work describes the measurement of specific heat and particle thermal conductivity of softwood (SW), softwood bark (SB) and therein derived softwood char (SC). Differential scanning calorimetery (DSC) was used to measure the specific heat. At 313 K, the measured specific heat was found to be 1172, 1364 and 768 J kg⁻¹ K⁻¹ for SW, SB and SC, respectively. The specific heat of SW and SB increased linearly from 1172 to 1726 and 1364 to 1777 J kg⁻¹ K⁻¹, respectively, with an increase in temperature from 313 to 413 K. With an increase in temperature from 313 to 713 K, the specific heat of SC doubled from 768 to 1506 J kg⁻¹ K⁻¹ and followed a polynomial relationship with temperature. A modified Fitch apparatus was constructed, calibrated and used for measurement of particle conductivity of SW, SB and SC. The particle thermal conductivity of SB was found to be twice that of SC, i.e. 0.2050 and 0.0946 W m⁻¹ K⁻¹, respectively, at 310 K. The particle thermal conductivity of SW, SB and SC followed a linear increase with temperature.