Journal of Engineering and Technological Sciences
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Experimental Work for Bar Straightness Effect Evaluation of Split Hopkinson Pressure Bar
Get PDFBar straightness is one of several factors that can affect the quality of the strain wave signal in a Split Hopkinson Pressure Bar (SHPB). Recently, it was found that the bar components of the SHPB at the Lightweight Structures Laboratory displayed a deviation in straightness because of manufacturing limitations. An evaluation was needed to determine whether the strain wave signals produced from this SHPB are acceptable or not. A numerical model was developed to investigate this effect. In this paper, experimental work was performed to evaluate the quality of the signal in the SHPB and to validate the numerical model. Good agreement between the experimental results and the numerical results was obtained for the strain rates and stress-strain relationship for mild steel ST37 and aluminum 6061 specimen materials. The recommended bar straightness tolerance is proposed as 0.36 mm per 100 mm
The Effect of Acids on Alkaloid Yield in Pressurized Water Extraction of Narcissus Pseudonarcissus
Get PDFPressurized water (PW) extraction of galanthamine from Narcissus pseudonarcissus bulbs was performed. The obtained yield was compared with the yield from conventional acidified water extraction and methanolic Soxhlet extraction. Both PW and conventional acidified water extraction were followed by a subsequent purification step for the alkaloids. The PW extraction (70 °C, 150 bar, 45 min) yielded as much galanthamine as methanolic-Soxhlet extraction (ca. 3.50 mg/g). Meanwhile, acid-base extraction with 1% of HBr (v/v) at 65 °C for 3 h gave a lower yield (ca. 2.65 mg/g). A higher PW temperature did not significantly increase the galanthamine yield. Pressure increase is not necessary since more water-soluble compounds such as proteins and polysaccharides are co-extracted, resulting in high viscosity of the water extract solution, which hampers the filtration process. Hence, the acidity of the solution is highly important both in the case of PW extraction and acidified water extraction. Besides galanthamine, the total alkaloid profile following Narcissus alkaloids was also obtained. Lycoramine, O-methyloduline, norgalanthamine, epi-norgalanthamine, narwedine, oduline, haemanthamine, O-methyllycorenine, and a haemanthamine derivate were identified. Although a high yield was obtained from PW extraction, the further purification needs to be improved to obtain an economically feasible industrial extraction process
Global Inversion of Grounded Electric Source Time-domain Electromagnetic Data Using Particle Swarm Optimization
Get PDFGlobal optimization inversion of grounded wire time-domain electromagnetic (TDEM) data was implemented through application of the particle swarm optimization (PSO) algorithm. This probabilistic approach is an alternative to the widely used deterministic local-optimization approach. In the PSO algorithm, each particle that constitutes the swarm epitomizes a probable geophysical model comprised by subsurface resistivity values at several layers and layer thicknesses. The forward formulation of the TDEM problem for calculating the vertical component of the induced magnetic field is first expressed in the Laplace domain. Transformation of the magnetic field from the Laplace domain into the time domain is performed by applying the Gaver-Stehfest numerical method. The implementation of PSO inversion to the TDEM problem is straightforward. It only requires adjustment of a few inversion parameters such as inertia, acceleration coefficients and numbers of iteration and particles. The PSO inversion scheme was tested on synthetic noise-free data and noisy synthetic data as well as to field data recorded in a volcanic-geothermal area. The results suggest that the PSO inversion scheme can effectively solve the TDEM 1D stratified earth problem.
Extreme Significant Wave Height Map of Indonesia Based on SEAFINE and ERA5 Database
Get PDFSignificant wave height, , is one of the most utilized ocean parameters. Extreme with 1-yearly and 100-yearly return periods are required for the design of most offshore structures. A previous study by Wurjanto, et al. (2020) attempted to utilize the SEAFINE database to develop extreme maps of Indonesian seas. However, SEAFINE does not cover the eastern Indonesian seas. This study analyzed the extreme values from ERA5 data for Indonesian seas and utilized the data to complete the extreme map previously developed by Wurjanto, et al. (2020). The ERA5 data on the eastern Indonesian seas as well as the central and western seas were extracted for validation purposes. The ERA5 extreme value was less than half the value compared to the SEAFINE-based results in most intersecting areas. For the development of the map, we took the SEAFINE-based map from Wurjanto et al., which covers the western and middle Indonesian seas, and filled the eastern part with extreme ERA5 data. It was found that a wave height multiplying factor of 2.0 was the most suitable for ERA5 in the developed map to make a seamless wave height transition from SEAFINE to ERA5 data
Extraction of Free Fatty Acid Mixtures from Rice Bran Oil by Aqueous Renewable Alcohols: Liquid-liquid Equilibrium Diagram and Number of Equilibrium Stages
Get PDFThis work is aimed to measure the liquid-liquid equilibria of rice bran oil-fatty acid-aqueous alcohols using fatty acid mixtures derived from rice bran oil as solutes and to calculate the number of equilibrium stages required for the extraction process. Renewable alcohols, ethanol and isopropanol in aqueous form were used as solvents. The liquid-liquid equilibrium data were measured at 25 °C and presented as ternary diagrams. It was found that ethanol gave a lower distribution coefficient than isopropanol. For the same solvent, increasing the water content resulted in a lower distribution coefficient. For the free fatty acid contents of 30% in the feed and of 10% to 2.5% in the raffinate, the minimum solvent-to-feed ratio was found to be in the range of 1 to 5. Using solvent-to-feed ratios from 2 to 4, the number of extraction stages required was in the range of 1 to 8. Based on the minimum solvent-to-feed ratio and number of equilibrium stages, isopropanol was found to be better than ethanol
COVID-19 Prevention: Role of Activated Carbon
Get PDFRecently, Coronavirus Disease 2019 (COVID-19) has brought the whole world into a pandemic condition, where the number of infected cases and deaths is exponentially high. A number of vaccines are available for this novel virus, but these are in the preliminary stage and are also not available to everyone. As the virus is very contagious, protection and prevention are the best way to survive and get rid of this disease. The virus affects the human body by entering through the nose, mouth, and eyes, so face protection with an appropriate mask is highly advisable. Combined masks made with activated carbon (AC) can effectively adsorb the virus because of its high surface area and broad functional groups. Such combined masks can also control coronavirus transmission by capturing harmful gases and smoke as they help in decreasing the spread of the viru