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Effect of voltage variation on the properties of gas tungsten arc welded low carbon steel
Full text linkThis research was necessary as only limited work had been carried out on the effects of arc voltage on the mechanical properties of welded low- carbon steel using Gas Tungsten Arc Welding (GTAW). Even though it is pretty expensive compared to other welding types due to the required shielding gas, GTAW processes have the advantage of being automated with continuous feeding of the electrode into the weld and avoiding the production of fused flux or slag layer. It becomes imperative to determine the effect of welding parameters on the microstructure and mechanical properties of welded joints using GTAW at a fixed current (115A) but with varying voltage. The low carbon steel specimen employed has a thickness of 5 mm, while the electrode used was the E6013 electrode with a tungsten size of 2.4 mm and a filler rod size of 3.2 mm. The effects of voltage variations at different levels, specifically 200V, 205V, 210V, 215V, 220V, and 225V, on the microstructure and mechanical properties of GTAW weldments were investigated. Adjusting voltage levels while maintaining a constant current of 115A increased hardness values and decreased tensile strength and impact toughness compared to the unwelded sample. The increase in hardness of the welded steel can be attributed to the formation of a fine grain structure and intermetallic phase, as observed in the micrographs. Also, the ultimate tensile strength, ductility, and Young’s modulus decrease as the voltage increases from 200V to 210V, followed by an increase as the voltage rises from 215V to 225V compared to the unwelded sample. The observed variances in the properties of the material were attributed to the high concentrations of sulfur (0.07%), manganese (1.48%), and phosphorus (0.22%) present in both the base metal and electrode utilized
Computational algorithm for fractional Fredholm integro-differential equations
Full text linkFractional calculus is a fascinating field of mathematics that focuses on the study of integrals and derivatives of arbitrary orders, extending the principles of basic calculus. Its applications span across various scientific, engineering, and other disciplines. In this study, the collocation method, in conjunction with the utilization of the fourth kind Chebyshev polynomials, is employed to explore solutions for fractional integro-differential equations of Fredholm type. By applying the collocation method, the problem at hand is transformed into a system of linear algebraic equations. These equations are subsequently solved by employing matrix inversion techniques to determine the unknown constants. To provide a comprehensive understanding and visualization of the results, the research incorporates tables and figures, which present numerical examples and comparisons. These comparisons serve to highlight the superior performance of the proposed method in terms of efficiency and convenience when compared to traditional methods. By showcasing the advantages of the collocation method and the utilization of fourth kind Chebyshev polynomials, the research underscores the potential of these approaches in solving fractional integro-differential equations
On the interaction of the human immune system with foreign body: mathematical modeling approach
No full textIn this study, we present a simple but novel mathematical model to show the interaction of the five immunological cells in the lymphocyte family – the cytotoxic-Lymphocytes (T), B-cell antibody, killer T – cell (K), the helper T – cell (H) and the Regulatory T – cell (R) –with foreign bodies with or without treatment. The feasibility of the model and important parameters of invasion in mathematical epidemiology: the reproductive number, free and infection persistence equilibrium, local and global stability among others were established. Results confirm the effectiveness of booster (vaccination or drugs) of these cells (of the immune system as recovery of infected cells is quicker and sustainable with vaccinations that boost these body cells. By this study drug producers are better informed about the effectiveness of the boosting components of vaccination and drugs they produce and health workers have good insight and handful understanding of the efficacy of drugs and vaccines administered in the treatment of virus infection
Influence of sawdust particles reinforcement on physical and mechanical properties of High-Density Polyethylene (HDPE) matrix composites
Full text linkThe influence of sawdust particles reinforcement on the physical and mechanical characteristics of high-density polyethylene (HDPE) matrix composites was studied for application as sustainable wood plastic composites (WPCs) for housing. The WPCs developed by compression moulding method were characterised. The results revealed web-like structures/cross-linking in the microstructure of the samples, which is a characteristic of polymers. The microstructure revealed a good dispersion of sawdust particles and compatibilizer in the HDPE matrix and bonding, which enhanced the properties of the composites. The control sample C exhibited water absorption of 0.22 % whereas sample S8 having 1.1 to 1.4 mm sawdust particles, 30 wt. % of sawdust particles content, and 3 wt. % of compatibilizer exhibited the least water absorption of 0.14 %. The unreinforced HDPE control sample exhibited a tensile strength of 12.53 MPa while sample S7 with the smallest size (less than 1 mm) and 30 wt. % of sawdust particles content, and 7 wt. % of compatibilizer exhibited the highest tensile strength of 16.22 MPa. This is 29.5 % higher than that of the control sample. The control sample exhibited a flexural strength of 10.2 MPa while sample S7 exhibited the highest flexural strength of 14.85 MPa, which is 45.6 % higher than that of the control sample. The control sample exhibited a hardness value of 13.93 HV while sample S7 exhibited the highest hardness value of 19.17 HV, which is 37.6 % greater than that of the control sample. Samples S5, S7, S8, and S9, which contained high content of sawdust particles demonstrated impact energy values of 34.27, 33.14, 35.17, and 36.46 J respectively. The unreinforced control sample demonstrated a low wear rate value of 0.35 g/Nm. However, sample 7 demonstrated the least wear rate of 0.23 g/Nm, which is 34.3 % lower than that of the control sample. In view of these characteristics, the composites especially sample 7, has the potentials for application as a sustainable building material
Study of the mechanical properties of bamboo and glass fiber reinforced hybrid polymer matrix composites
Full text linkBamboo and glass fibers reinforced hybrid epoxy matrix composites were produced by stir casting method and the effects of production parameters (temperature, drying time, particle concentration, and bamboo-to-glass fiber ratio) on the mechanical properties were investigated. Overall optimum fabrication parameters are a bamboo fiber drying temperature of 25 ○ C, a drying time of 20 mins, a particle size of 0.75 mm, and a bamboo-to-glass fiber ratio of 1:3. An in-depth analysis of the results shows that the improvement of different composite properties can be specifically targeted using different parameter combinations. Specifically, the shortest fibers below 0.75 mm, dried at room temperature for 60 minutes, and a bamboo-glass fiber ratio of 1:3 yielded the highest tensile strength of 7.47 MPa, which represents about 120 % increase as compared to unreinforced epoxy. Similarly, the longest fibers between 1 to 2.8 mm, dried at 110°C for 60 minutes, and a bamboo-glass fiber ratio of 1:1, exhibited the highest impact energy of 37.2 J, corresponding to about 79 % improvement. Moreover, the medium length fibers between 0.75 and 1 mm, dried at 80 ○ C for 60 minutes, and a bamboo-glass fiber ratio of 3:1, exhibited the highest hardness of 16.73 HV, translating to 37% increase. Sample S8, which is the hybrid reinforced composite containing 0.75 mm bamboo fiber-particle size exhibited the lowest wear rate of 1.09 g/Nm implying the highest wear resistance. All these show the effectiveness of the mixture of bamboo and glass fibers in improving the mechanical properties of the composites. However, excessive bamboo concentration led to a significant reduction in wear properties
A comprehensive geospatial analysis for optimal waste disposal site selection: integrating environmental, social and economic factors
Full text linkUncontrolled city growth and quick development have made solid waste management a global challenge. Choosing the wrong disposal site leads to economic, physical, and environmental losses, impacting the human environment deeply. The aim of this paper is to discuss on geospatial analysis for optimal waste disposal site selection integrating environmental, social and economic factors. Among various methods, the combination of Geographic Information System (GIS) and Analytical Hierarchy Process (AHP) based on Multi Criteria Decision Analysis (MCDA) has proven to be a good way to find suitable landfill sites. This paper also presents the selection of the best and most scientific landfill sites within Kavrepalanchowk District of Nepal. In this study, seven criteria are taken into account: distance to water bodies, distance to road, and distance to settlement area, slope percentage, soil type, geology, and forests. Each rating map is created using GIS environment and the weight is obtained from the AHP pairwise comparison matrix. The map showing suitable sites for waste disposal is obtained by using the weightage overlay tool and assigning the weightage to each criterion
Does Mccutcheon’s mortality polynomial matrix actually account for mortality decline at ten years?
Full text linkThis paper intends to employ a non-parametric technique as an alternative technique of modelling and estimating the instantaneous mortality rate intensities which serves as the underlying basis in modeling the distribution of future lifetime. It relies heavily on the analytic properties of life table survival functions lx . The specific objectives of the study are (i) to derive models for the force of mortality using polynomial function (ii) to derive the survival function (iii) to detect the age at which mortality actually declines and (iv) estimate the curve of death. Computational evidence from our results confirms that in the models 1-3, the mortality intensity µx and the curve of death µxlx are not both defined within the age band 0 ≤ x ≤ 2. The implication is that the infant mortality cannot be captured and the model is not admissible within this interval. Furthermore, it is also observed that µx = µ is constant within the interval 2 ≤ x ≤ 9 and mortality declines at age x=10. Consequently, there is a visible improvement in the care of infants which accounts for the decline in infant mortality. In model 4 since lx < l(x−1) < l(x−2) < l(x−3) < l(x−4) < l(x−5) < l(x−6), it then becomes apparent that µx < 0. The fact that the force of mortality becomes negative represents a phantom detected from the McCutcheon’s mortality matrix
Detection of fake news using deep neural networks
Full text linkWith the increased use of the Internet and social networking sites, information can now disseminate at a rapid rate. It is an age of information where any information can be accessed with a single click. This has increased the risk of the spread of misleading false information. These fake news have negatively impacted people and society. So, a strong mechanism is needed to detect false news and stop its propagation. The content of the news, the source of the news, and the response to the news are the main features that can help to detect the credibility and authenticity of the news. This paper aims to implement deep neural networks to accurately detect fake news. It aims to evaluate the various deep learning models to determine the model that can accurately and efficiently distinguish fake news. The experiment uses the Source Based Fake News (SBFN) dataset, a publicly available dataset for Fake News Detection. Various deep learning models such as Long Short Term Memory (LSTM) and Bidirectional Encoder Representations from Transformers (BERT) along with a hybrid model have been trained and evaluated on this SBFN dataset
An overview of agricultural mechanization in Nepal
Full text linkIncreased migration of the youth from Nepal has created a demand for mechanization in Nepalese agriculture. The systematic agricultural mechanization can lead towards the sustainable agricultural commercialization for a prosperous Nepal. This paper analyzes the efforts, status, and policies related to agricultural mechanization and recommends policy reforms to align with the new constitution of the Federal Republic of Nepal, institutional capacity building, business development, favoring local production of agricultural machinery, promotion of custom hiring in business model, capacity development, promotion of women-friendly technologies, equitable agricultural mechanization program, and an integrated effort for sustainable agricultural mechanization through a public-private partnership model
Design and numerical analysis of a horizontal axis wind turbine
Full text linkIn this paper, mathematical design of a 20 kW horizontal axis wind turbine is conducted along with computational analysis to verify the performance of the designed blade. Blade Element Momentum (BEM) theory is used for the design of blades, empirical BEM relations for geometry calculations for twist distribution and chord distribution are included. The computational analysis on the performance of the geometric design is done using both BEM and Computational Fluid Dynamics (CFD) through Qblade BEM code and ANSYS CFX tool respectively. The rotational periodicity based domain is used for CFD computation and k- ϵ turbulence model is considered. The analysis is done in variable speed conditions (constant tip speed ratio of 6) for wind speed range 2-12 m/s, and change of pitch angles from 1 to 4°. The optimum pitch is obtained as 3° from CFD analysis. The results of torque, Cp/Power, velocity streamlines, and pressure contours are obtained from CFD. Torque curve obtained from BEM and CFD analysis over wind speeds 2-12 m/s showed good agreement, supporting the HAWT geometric design. A maximum Cp of 0.399 was obtained at 12 m/s