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A Comparative Study of Green Geopolymer Concrete Using Fly Ash
Get PDFIn this work, the long-term properties of low-calcium fly ash-based geopolymer concrete were studied. The long-term properties included in the study were compressive strength, sulfate resistance, and sulfuric acid resistance. Fly ash-based geopolymer concrete in this study utilized the low-calcium (ASTM Class F) dry fly ash as the source material. The alkaline liquid comprised a combination of sodium silicate solution and sodium hydroxide solids in flakes or pellets form dissolved in water. The coarse aggregates were crushed granite-type aggregates comprising 16 mm, and the fine aggregate was fine sand. High-range water reducer superplasticizer was used to improve the workability of fresh geopolymer concrete. The mixture proportions used in this study were developed based on a previous study on fly ash-based geopolymer concrete. Two different mixing ratios, M15 and M20, were used for the fly ash concrete, cement concrete, and a mixture of cement+fly ash concrete specimens. Test specimens were manufactured in the laboratory using the equipment normally used for Portland cement concrete, such as a pan mixer and steel molds. For sulfate resistance tests, the test specimens were immersed in 4% sodium sulfate solution for a period of exposure up to one week. The sulfate resistance was evaluated based on the change in mass, change in length, and change in compressive strength of the specimens after sulfate exposure. The test specimens were 150x150x150 mm cubes. The sulfuric acid resistance of concrete was also studied. The concentration of sulfuric acid solution was 5% for soaking concrete specimens. The sulfuric acid resistance of concrete was evaluated based on the mass loss and the residual compressive strength of the test specimens after acid exposure up to one week. For each type of test, companion specimens were prepared and tested to determine the 7th day and 28th day compressive strength
Development of Some Common Fixed Point Theorems in Semi-Metric Space
Get PDFThe purpose of this paper is to briefly study the development of some common fixed point theorems in semi-metric space. 
Determination of Earthquake Magnitudes Using Duration of High-Frequency Energy Radiation and Maximum Displacement Amplitudes: Application to the April 25, 2015 Nepal Earthquake
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Influence of Welding Variables on the Microstructural and Tensile Properties of 304L Austenitic Stainless Steel Heat Affected Zone
Get PDFThis work investigates the effects of welding speeds and power inputs at different ranges on the Heat Affected Zone (HAZ), microstructural characteristics, and tensile behavior of type 304L austenitic stainless steel. Chemical analysis of the as-received 304L austenitic stainless steel was done to determine its chemical composition. Thereafter, the as-received 304L austenitic stainless steel plate was cut with a hacksaw into samples of dimensions 70 mm length, 45 mm breadth, and 8 mm thickness. Thirty samples were produced in all, with ten samples each assigned to groups A, B, and C respectively. The grouped samples were further cut into two equal halves with a hacksaw and welded using Gas Metal Arc Welding (GTAW) process and 304L electrode to produce butt joint HAZ square geometry samples. The obtained HAZ samples and as-received sample were machined to standard tensile test specimens, and tensile tests were made using standard approaches. The HAZ and as-received specimens were prepared for microscopy studies and etched in a solution of 1 ml HCl + 3 ml HNO3 + 1 ml glycerol, and the microstructures were examined using a metallurgical microscope at a magnification of 400x. Results obtained show that the microstructures are composed mainly of a mixture of austenite and ferrite phases. Also, variations in volume fraction and grain size of the phases were observed at the different welding speeds and power inputs. In addition, chromium carbide formation and precipitation due to sensitization were seen at the grain boundaries. Also, optimum ultimate tensile strength (UTS) and yield strength (YS) were obtained for HAZ sample at moderate (4.5 mm/s) welding speed, and optimum % elongation at slow welding speed. Optimum UTS and YS were obtained for HAZ sample at a power input of 9.2 KW, and optimum % elongation at 12.00 KW. Generally, when compared with the as-received sample, a remarkable influence of the welding variables on the tensile characteristics of the material’s HAZ was noticed
Automatic Detection of Opinion Polarity and Their Strengths in Newspaper Editorials
Get PDFIn this paper, we discuss the development of our methods in performing analysis on the newspaper editorial. We discover that analyzing editorial texts for opinion polarity and strength is a daunting task. It poses several challenges – implicitness of opinions, unpredictable situation with opinion polarity and strength, variance in the language expressions and so on. We evaluate the resource based approach in detecting opinion polarity and strength thereby measuring the effectiveness of the different lexicons and rules provide current results before the last line. The results show that the current accuracy are quite low and this approach requires further efforts to achieve better scores
Process Safety in the Radical Polymerization of Styrene: From Bulk to Solution/Emulsion Process
Get PDFIn this study, the influence of process parameters on the behaviour of free radical homo-polymerization of styrene in a well mixed batch reactor was examined. The reaction of styrene with itself in hydrocarbon solvents of dissimilar polarities (acetone and chloroform) and non-hydrocarbon solvent (distilled and de-ionized water) was studied experimentally over ranges of solvent volumes, temperature, reaction time, and initiator type in a magnetically stirred thermo-well round bottom reactor. Similar reactions were carried out using equi-volumes of the solvent blend to explore the possibility of solvent synergy. This study uses the kinetic model of Coats-Redfern to evaluate kinetic parameters such as activation energy, order of reaction, and rate constant. This aspect becomes especially important as it is necessary to know in advance the parameters that will assist the occurrence of runaway reaction. The right choice of operating conditions of the styrene polymerization of known kinetics according to this study is a defense mechanism against runaway reaction. Although not discussed in this study, mischarging of reactants, maintenance troubles, agitator breakdown, etc. may also cause runaway reactions. Solution molecular weights of polystyrene samples were measured using the Mark-Houwink Sakurada equation and other procedures earlier reported. The gel effect and heat accumulation within the reactor system were less pronounced, giving a safety advantage to the solution/emulsion process compared to bulk. Further dilution of the monomer with the solvents effectively reduces the gel effects. Unlike in thermal polymerization process, the type of initiator and their mass concentration in the reacting mixtures reduce the reaction time, thereby minimizing the use of energy, making the process cost-effective
Waste Vegetable Oil: A Boon for Biodiesel Production
Get PDFEdible Waste Vegetable Oils (WVO) pose a potential threat to water quality, putting pressure on community water treatment facilities due to their recalcitrant nature. Repurposing them as feedstocks for biodiesel production through the trans-esterification process offers a sustainable solution to address water pollution while meeting the rising demand for fuel. This study aimed to synthesize biodiesel from WVO using an indigenously designed, modular, and mobile biodiesel reactor plant capable of producing 40 liters of biodiesel per day. The biodiesel obtained underwent standard fuel tests, and the results aligned well with the corresponding ASTM standards, ensuring quality and reliability. With a cost of just thirty rupees per liter, the biodiesel proved to be economically viable. Field tests were conducted to evaluate its performance, including blending it at a 20% level with commercial diesel in heavy motor vehicle fuel tanks and using it as a boiler oil fuel for water heating. Additionally, the incidental by-product, glycerol, was found to have commercial value, further enhancing the sustainability of the biodiesel production process
Mathematical Study of Biting Rates of Mosquitoes in Transmission of Dengue Disease
Get PDFThe paper utilizes the SIR model to analyze the spread of the dengue disease, considering various biting rates of mosquitoes. Within the model, the human population is categorized into susceptible, infected, and recovered compartments, while the mosquito population is divided into susceptible and infected compartments. Through the calculation of the basic reproduction number, the study evaluates the transmission dynamics of dengue. Additionally, a sensitivity analysis is conducted to assess the significance of different model parameters in influencing disease transmission
Diagnostics of Low Pressure DC Glow Discharge Using Double Langmuir Probe
Get PDFThis paper reports the result of electrical diagnostics of low pressure DC glow discharge using Langmuir double probe. The electron and ion distribution function at the probe sheath edges are considered to be Maxwellian so that the most important requirement of pre-sheath and sheath transitions are satisfied. The electrons and ions are assumed to penetrate the sheath region due to their large thermal velocities. Using the probe biasing technique, the discharge plasma parameters like electron temperature (KTe) and electron number density (ne) are measured at the applied voltage ranging from 400V to 700V, between the two electrodes, and pressure, inside the discharge tube, ranging from 0.013mbar to 0.070mbar. Our result showed that electron temperature (KTe) and electron number density (ne) increases with the pressure inside the discharge tube and applied voltage across the electrodes
A Study on Electric Dryer for Cash Crops Drying as an End-Use Promotion of Micro Hydro Power in Nepal & Its Comparative Analysis with Biomass Based Drying System
Get PDFElectric dryers serve farmers as an efficient, environment friendly, and proper technology with high performance for quality product drying than other types of conventional dryers. Development and implementation of electric dryers have become a must to bring socio-economic and technological change in rural Nepal. For performance testing and comparison with biomass-based drying systems, an electric dryer was designed and locally fabricated, taking special care in insulation of the system and transported to Baletaksar-5, Gulmi. Performance testing was followed by individual parts testing with the observation of drying pattern. Two different performance tests were carried out with 25 kg of fresh ginger as input, which was dried for 4.5 hours. The first test was 30% efficient, consuming 40 kWh of electric power with an output of 5.4 kg of dried ginger. When leakage of the hot and dry air from the dryer was minimized in the second test, the dryer was 37% efficient. Later on, the electric dryer system was compared with a biomass-based dryer system, which shows that the drying rate of the electric dryer is stable and constant, also the required temperature in this system can be maintained as per requirement like 60°C in the case of ginger drying. The temperature profile of drying air in the biomass-based system was unstable and inconsistent with periodical variation like a sinusoidal curve. The efficiency of the electrical dryer was much higher compared to the biomass-based system, which lies between 10 to 13% depending upon feedstock input for gasifier. Financial analysis was performed, which shows an annual revenue of NRs. 2,340,000 with a total breakeven sales of 4379.5 kg dry ginger and corresponding payback period is 0.9357 years