Journal of Engineering and Technological Sciences
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Underwater Acoustic Power Around Submerged Body in Shallow Water Using Boundary Element Method
Get PDFUnderwater acoustic power around a submerged body in shallow water was investigated using the Boundary Element Method (BEM). The model domain simulated a nearshore environment with shallow water conditions. The seabed was assumed flat and sound velocity was constant over depth. The boundary element method was combined with eigenfunction expansion to model radiation boundary conditions. Underwater acoustic power was calculated from the underwater acoustic potential in the domain. Several cases were investigated in this study: cases with variation of submerged body distance from the seabed, variation of submerged body location from the underwater acoustic source, and variation of submerged body length
Prestressed Concrete I-Girder Optimization via Genetic Algorithm
Get PDFPrestressed concrete has been gaining popularity in the construction industry because of its many advantages, which include reduced dead load due to less material used and overall cost savings. Nonetheless, a single prestressed concrete I-girder as a structural element in highway bridges is still significantly costly and massive, so optimization can yield a significant amount of cost savings as well as reduced material consumption. In this study, prestressed concrete I-girder optimization was carried out by implementing a genetic algorithm (GA), a method inspired by nature's evolution and natural selection. This study evaluates a number of aspects of applying a genetic algorithm for optimization of material cost of a prestressed concrete I-girder design. A new method for calculating the fitness value is proposed, which was proven to be essential for the application developed in this study. The best solution that resulted from the optimization process is presented, defined by being the least costly solution while still maintaining compliance with the AASHTO LRFD 2007 design code, which includes ultimate strength, service stresses and deflection, detailing requirements, geometrical feasibility, etc. Lastly, a sensitivity analysis was carried out, discussing the influence of the starting conditions on the output of the optimization process
Drought Event Analysis and Projection of Future Precipitation Scenario in Abaya Chamo Sub-Basin, Ethiopia
Get PDFMonthly observed and future precipitation magnitudes were subjected to statistical trend analysis to examine possible time series behavior. Future precipitation was downscaled from large-scale output through statistical downscaling. The observed and downscaled future precipitation was analyzed for drought events using the Standardized Precipitation Index (SPI) method. In the Abaya Chamo sub-basin, Ethiopia precipitation is explained by below average magnitudes in most of the low land area, characterized by moderate to extreme drought episodes. Nine drought events were discerned during the period of 1988 to 2015, i.e. once in three years, resulting in harvest failure and subsequent food insecurity. The NCEP-NCAR and CanESM2 model predictors were used to statistically downscale the precipitation data. The monthly observed and downscaled precipitation magnitudes were in good agreement. The RCP-2.6, RCP-4.5 and RCP-8.5 long-term future scenarios were computed to evaluate future drought patterns. The mean annual precipitation scenario decreased by 0.2% to 13.7%, 0.5% to 6.4% and 0.1% to 1.3% for the period from 2016 to 2040, 2050s and 2080s respectively. The increase in mean precipitation was projected to be 0.7% to 12.2%, 0.2% to 11.7% and 0.1% to 17.8% for the period from 2016 to 2040, 2050s and 2080s respectively. The present analysis may provide useful information associated to drought events to decision makers and can be used as a basis for future research in this area
Viscosity Measurement of Blended Patchouli Oil at Atmospheric Pressure and Room Temperature
Get PDFPatchouli is an essential oil used in perfumes, cosmetics, soaps, insect repellents and also a candidate for biodiesel from non-edible oil. Patchouli oil from Aceh Province, Indonesia, is generally produced using a distillation process. The relationships between physical properties, i.e. the viscosity and quality, of patchouli oil from Aceh Province and blends with other oils, were investigated. The mixture oils used were palm oil, kerosene and lubricant oil SAE 40. The mixture compositions were 100:0; 75:25; 50:50; 25:75 and 0:100 (v/v). It was found that mixing palm crude oil (25%) or lubricant oil (25%) with patchouli oil increased the viscosity by about 41% and 72%, respectively, compared with pure patchouli oil. A 53% decrease in viscosity was observed when the patchouli oil blend contained 25% kerosene. Natural variation in patchouli alcohol (PA) and iron (Fe) content in the patchouli oil sample was found to increase the value of viscosity by up to 1.5%
Quantitative Analysis of Interfacial Area on Liquid-liquid Multiphase Flow of Transesterification Process in Cross-junction Microchannel Reactor
Get PDFKey advantage of microfluidic technology in chemical processing is the high interfacial area which is especially important factors in multiphase reaction. The multiphase reaction like transesterification of vegetable oil and methanol to produce biodiesel are largely dependent on interfacial area for better mass transfer. However, little attentions have been given to the hydrodynamic factor which affects the interfacial area in a microchannel. In this study, the interfacial area from the droplet flow regime was studied by varying the parameter of methanol to oil ratio (M/O), total flow rate (QTotal) and catalyst concentration. The droplet flow was created by a cross-junction channel and photos were made to measure the size of the droplets with help of microscope. The maximum M/O ratio of 23 and lowest flow rate of 10 μL/min exhibited the highest interfacial area, where increasing M/O by 67% could increase the interfacial area by 23%. By varying the KOH catalyst concentration, the change in the interfacial area was very small, hence showing the lowest impact on the interfacial area of the droplet. Therefore, further analysis must be performed to investigate the impact of interfacial area and mass transfer coefficient on the reaction performance to produce highest yield of biodiesel in microchannel reactor
DBSA-Catalyzed Sewage Sludge Conversion into Biodiesel in a CSTR: RSM Optimization and RTD Study
Get PDFSewage sludge from the primary stage of a wastewater treatment plant (WWTP) in Al-Diwaniyah City was direct-transesterified to biodiesel using dodecylbenzenesulfonic acid catalyst in a system with two continuously stirred tank reactors. The response surface and the central cube design methodologies were used to optimize the parameters affecting the biodiesel yield. The optimum conditions for the process in this study were found to be (residence time: 90 min; catalyst loading 8 wt%; methanol/oil ratio: 18; reaction temperature: 368.15 K). Under the optimum process conditions a biodiesel yield of 96.51% was obtained. The experimental residence time distribution (RTD) was calculated and compartment models were applied for the two-tank reactor system. In the CSTR, a dead zone of (10 liter) was estimated. The independent analysis of fatty acids in the sewage showed that the lipids consisted primarily of palmitic acid (C16:0 = 37.86), oleic acid (C18:1 cis-9 = 19.72) and stearic acid (C18:0 = 17.32), and the acid value was (2.44 mg KOH/g). The properties of the biodiesel produced were comparable with the ASTM D-6751-2 standard and the properties of mineral diesel
Minimizing Electricity Fuel Cost of Thermal Generating Units by Using Improved Firefly Algorithm
Get PDFThis paper presents the application of an improved firefly algorithm (IFA) for minimizing total electricity generation fuel cost while all loads are supplied by thermal generating units. The proposed IFA was developed by combining two proposed improvements of the firefly algorithm (FA), i.e. improvement of the distance between two considered solutions and improvement of the new-solution production technique. The effect of each proposed improvement on the conventional firefly algorithm (FA) and the performance of IFA were investigated in two study cases, i.e. single- and multi-fuel option based thermal generating units. In the first case, three different systems with three, six and twenty units were employed, while a ten-unit system with four different loads was tested in the second case. The comparison results between IFA and existing methods, including three other FA variants, revealed that the two proposed improvements of FA are very efficient and make IFA a very promising meta-heuristic algorithm for minimizing fuel cost of thermal generating units
A Strategy for Sustainable Development: Using Nanotechnology for Solar Energy in Buildings (Case Study Parand Town)
Get PDFSolar energy is a source of free and clean energy that has no harmful environmental effects. Simple applications of new technologies such as nanotechnology are a cost-effective way of using renewable energy, which has led many industries to invest in this area. In this descriptive-analytical study the utilization of solar energy in a hot and dry region of Iran was investigated as a useful and safe resource for supplying the energy needed for the construction of Parand town, considering the available climatic potentials. The statistical population in this study was a group of inhabitants of Parand town, employees of the Tehran Construction Engineering Organization and experts in the field, from which 384 participants were selected by simple random sampling. After collecting field information through a questionnaire, the relationships between the variables of the study were tested by SPSS. The result of the study showed that the most important achievements of using nanotechnology for solar energy in view of the sustainable development of building construction from the participants' perspective were photovoltaic coating on building roofs (58.7% of the participants' responses), nano solar water heaters (57.4% of responses) and active solar cell dryers (22.1% of responses) respectively
Results Comparison for Hat-shaped, Double-notch and Punch Testing of Split Hopkinson Shear Bar Technique
Get PDFThe split Hopkinson shear bar (SHSB) test is a modification of the high rate-impact test using a split Hopkinson pressure bar (SHPB). The SHSB has been developed for a variety of techniques, for example, the hat-shaped (circular or flat), double-notch, and punch (with or without notch) techniques. The main purpose of this study was to compare these three techniques to determine the shear stress-shear strain of aluminum alloy 2024-T351. The study was conducted using the Abaqus/CAE® software. The circular hat-shaped and punch (with and without notch) techniques used a quarter-section solid 3D model. The flat hat-shaped and double-notch techniques used a half-section solid 3D model. This study successfully tested and compared the three SHSB techniques, with a number of considerations, i.e. the same parameter values for kinetic energy, shear area and shear angle. Each technique has its own advantages and disadvantages in terms of force equilibrium, flow stress fluctuation, constant strain rate, machine-ability, ease of experiment, etc. The optimum technique among the three is the hat-shaped technique