Advanced Engineering Forum Vol. 40

Abstract: In this research paper, two different metal plates of aluminum alloy viz. AA6061 and AA6101 were welded with friction stir welding process. Round tool and square tool pin profiles were used to weld the alloys. Weld microstructures, hardness, and tensile properties were evaluated in as-welded condition. The tensile strength of the joints fabricated with round tool pin profile were lower than the square tool pin profile because of the pulsating effect, in square tool pin profile this effect was produced along with the higher frictional forces. The micro-hardness of friction stir zone was higher than the base material due to active recrystallization occurrence which resulted in fine grain size in case of weld joint with round pin profile. Microstructure indicated uniformly distribution of materials with minimum heat affected zone and dense welded zone without any defects.

Abstract: The damping capacity improvement in under seawater for torpedo cone is the main of the research work. In the proposed work, an induction furnace was used to fabricate aluminum alloy AA7075 by melting individual elements such as pure Al, Zn, Mg, and Cu, followed by 10 wt.% graphite with varying sizes of reinforcement C1 (3 to 10μm), C2 (53 to 66μm), and C3 (106 to 150μm). Ingot casting was made in steel mold of 45 45 120mm³ and then hot forged at 490ᵒC, followed by solutionizing and artificial aging. Composites characterized for optical, SEM, hardness, and DMA analysis for loss factor. The improved performance in damping capacity by 50% observed for the threshold modulus of particulate (volume to the surface) for C2 composite. The processing cycle of fabrication of composites has been established.

Abstract: The need for the development of renewable energy harvesting and storage devices is on the front as the world is facing an environmental crisis due to the consumption of gallons of fossil fuels. One of the promising solutions on which many researchers are concentrating is supercapacitor as it possesses high energy and power density. Current literature study focusing on developments already had in the field of manufacturing of supercapacitors using different precursors, testing conditions, fiber dimensions, and their performance analysis. Most of the studies found that Polyacrylonitrile (PAN) based electrospun carbon fiber webs is a potential electrode material for supercapacitors. The information gathered in this article is about the electrospinning technique, Surface and electrochemical characterization methods, and recent advances in their performance are highlighted. Also, enhancement in electrochemical performance through optimization of electrospinning parameter, a precursor modification by the addition of active materials (such as carbon nanotubes, metal oxides, and catalysts), heat and surface treatment followed, and optimum fibrous structures are summarized.

Abstract: Nowadays, the solid residues of concrete are considered waste, and this have been transformed into an environmental problem. This study analyzes the use of aggregates that comes from the concrete demolition process in order to create recycled concrete. The use of this material reduces costs and mitigates pollution. The present research describes the comparison of concrete blends using Opuntia Ficus Indica as an addition and recycled coarse aggregates as a substitution against a control blend. Mechanical and non-destructive tests were performed to evaluate the performance of each mixture. A data science technique was used to generate artificial data to increase the number of data to be evaluated. Numerical models were established to find correlations between all the features that describe the materials. The use of recycled aggregates and the use of the Opuntia Ficus Indica improved the performance in all the tests made to the concrete. Additionally, different models based on regression trees were used to predict with high accuracy the compressive strength in this kind of material just considering the electrical resistivity as an input parameter.

Abstract: A steady, 2-D, viscous fluid flow past a fixed solid cylinder of radius ‘a’ has been considered where the density is constant for considered fluid. The flow of fluid happens in 3 regions namely fluid, porous and fluid region. The constitutive equations for the flow in porous and fluid regions are Brinkman and Stokes equations respectively. The variation of flow patterns by means of streamlines has been analysed by applying different boundary conditions at the interface of fluid – porous and porous – fluid regions and also on the surface of the solid cylinder assuming that the even velocity far off from the fluid region. The nature of streamlines is observed for the distinct values of porous parameter ‘σ’ and the corresponding flow behaviour is analysed graphically. From the obtained results it is noticed that increase in porous parameter, suppress the fluid flow in porous region consequently the fluid moves away from the solid cylinder.

Abstract: In Nigeria Arable land covers approximately 745,000km² of the total land area and at present organic farming is not prevalent, encouraged or facilitated despite its sustainability advantages. The anaerobic digestion process produces two main outputs (biogas and digestate). The digestate when properly harnessed can be used as a substitute for inorganic fertilizer. The digestate retains a high content of organic matter such as Nitrogen, Phosphorous and Potassium (K), as well as a range of other macro-and micronutrients like Calcium, Magnesium, Iron, Manganese, Zinc and ammonium. In this research work, a developed grass shredding machine for the composting of a digestate was evaluated for performance. Preliminary studies were undertaken to determine the liquid absorbability of non-shredded grass vise-visa dry shredded grass, the moisture content of fresh elephant and spear grass. An internal combustion powered shredding machine was developed to shred dry and sieve crushed grasses to be used as absorbent of digestate. The machine was evaluated for performance using different samples of properly dried elephant and spear grass. The shredded grasses samples were mixed with discharge digestate collected from a bio-digester to produce organic fertilizer. The shredding time, machine throughout capacity efficiency, mass of fibre and liquor were determined. The results of performance evaluation with elephant grass sample revealed that an average value of efficiency (90.97%), machine through put capacity (1.225g/sec), shredding time (126.54seconds), percentage loss (8.393%), fibre (288.58g) and liquor (119.83g) were established. Similar result were obtained with spear grass; efficiency (90.50%), machine through-put capacity (1.225g/sec), shredding time 126.54 seconds), percentage loss (8.32%), fibre (294.12g), and liquor (118.85g). The outcome of the results revealed that both solid fertilizer (fibre) and liquid fertilizer (liquor) were extracted from the digestate, and an average mass of 138.86g dried grass can absorb 269.55g of liquid digestate to produce organic fertilizer.

Abstract: Wind power has many benefits over other energy sources, including a high power density and an outstanding return on investment. However, there are some drawbacks, such as intermittent output power and the need for periodic maintenance. As a result, its output is substantially variable, making it difficult to predict and potentially causing system instability. Therefore, to model such a source, it is necessary to model the dynamic behavior of the wind turbine generator as well as the characteristics of the wind speed to capture the fluctuations. Furthermore, the durability and efficiency of the wind energy conversion system (WECS) are wholly dependent on the quality of the control strategy employed. In this paper, we introduced a control scheme, which makes it possible to find an optimal solution to the control problem while at the same time operating within the constraint point. Therefore, we designed the Model Predictive Controller to control and smoothly transition the wind turbine in all its operating modes while complying with its constraints. The main objective of using this control technique is to maximize power production while keeping the control action as simple as possible. The WECS used in this study is the horizontal axis wind turbines (HAWT), which are easier to control as their dynamics are not so complicated to model and, at the same time, produce maximum output power. The controller works have to adapt in the same way as the control goals are different for different wind speeds. Gain and weight scheduling strategies are used to design a control system that allows smooth transitioning between control regions. The dynamics of the wind turbine system and the controller are designed and simulated by the MATLAB / Simulink environment.