Advanced Engineering Forum Vol. 41

Abstract: This work aimed to compare the characteristics of micro and nanofibers of the poly (vinylidene fluoride) - PVDF polymer obtained by the Solution Blow Spinning (SBS) method, and films with those produced by other techniques, such as: casting and hot pressing. Thermogravimetric analysis (TGA) revealed that the films are thermally stable up to a temperature of 420 ° C. X-ray diffractometry (XRD) indicated the presence of the crystalline phases α and β, the β phase being more evident for nanofibers and PVDF casting. The film obtained by SBS showed a greater contact angle, showing to be more hydrophobic. Strain tests showed that the nanofiber films showed a 72% rupture to rupture, about 1.7 and 3.1 times greater than those obtained by casting and hot pressing, respectively. There was also a decrease in the modulus of elasticity and the limit of tensile strength of nanofibers, compared to other films.

Abstract: Highly demand of aesthetic needed made dental composites become a major role as dental restorations. Minimal invasive of sound tissue and the ability to mimic the original teeth also have the recommendation to choose dental composites. The developments of dental composites mostly focus on filler systems to improve mainly in the mechanical and optical properties due to the esthetic aspect of dental care recently has become increasing importance. According to the component of dental composites, the fillers had a big role to determine the properties of dental composite. Many kinds of fillers have been utilized to improve the properties. Two kinds of dental composites had been known based on their fabrication procedure; i.e. experimental and commercial. The experimental dental composites had been produced by the researcher on their formula to obtain good properties while commercial dental composites were made by many manufacturers which have each brand that has each product of excellence, especially in mechanical and optical properties. The aim of this review focused on the mechanical and optical properties of experimental dental composites and commercial dental composites including describes many factors that affect those properties.

Abstract: The purpose of this study is to investigate the impact of a V-shaped cutout on the buckling strength of E-glass epoxy composite laminates. In aircraft components, cutouts are more often used for inspection, ventilation, access to critical areas, fitting a particular component, and increasing the strength to weight ratio of the structure. In this paper, symmetric and antisymmetric laminates of E-Glass/Epoxy unidirectional are used and the effect of notch parameters such as notch radius(r), depth of the notch(h), and notch angle(α) is observed under monoaxial compression. Effects of end conditions and plate aspect ratio(l/b) are analyzed. It is observed that the notch radius does not have a considerable effect on buckling strength but the notch angle after 90⁰ shows a good dip in buckling loads as compared to 30⁰,45⁰, and 60⁰. Depth of notch and end conditions creates a considerable loss in buckling strength. As the h/b ratio is increased, the drop in buckling strength becomes significant. Clamped -pinned end condition of the plate gives a lower value of load multiplier as compared to clamped -clamped. As we increase the l/b ratio of the plate, buckling of the plate becomes easier. The position of the notch (a) also affects buckling strength which is maximum for a/l=0.25 and minimum for a/l=0.5.

Abstract: Hot corrosion is the main reason of failure of boiler tubes used at high temperature in thermal power plants. This paper is an attempt to investigate the effect of different composite coatings on boiler tube steel in corrosive environment of Na₂SO₄ – 60%V₂O₅ at 900°C for 50 cycles. The coatings have been deposited with high velocity oxy fuel process. The samples were exposed to hot corrosion in a Silicon tube furnace at 900°C for 50 cycles. The kinetics of corrosion behaviour were analysed by the weight gain measurements after each cycle. Corrosion products were analysed with weight change statistics, X-ray diffraction, and scanning electron microscopy. It is found that 100Cr₃C₂ composite coatings provided the higher resistance to corrosion as compared to other types of coatings. Cr carbide layer was formed on the surface and these layers provided the protection from hot corrosion.

Abstract: Landfill Leachates is one of the pollutants containing high organic matter and heavy metal which can cause toxic pollution to water due to less than optimal leachate processing. This study aims to introduce fine bubbles treatment to the leachate processing technology at the waste treatment facility at Sarimukti, West Java Indonesia. The toxicity test was conducted in the acute toxicity test and test for D. magna. The acute toxicity test was carried out using a static biological test according to APHA standards (1995). The LC₅₀-48 hours ware calculates using the Finney Probit Analysis Software. The results showed that the effectiveness of Sarimukti TPA leachate treatment was 97.5% DO, 71% BOD, 86% TDS, and 74.8% turbidity. The XRF spectra on the leachate after fine bubble found a recovery of heavy metal elements such as Cr, Mn, Fe, Zn, Cu, Pb, As, and Sn. Based on the Minister of Environment and Forestry Regulation, the effectiveness of leachate processing has reached the safe standard limit for pH, mercury, cadmium parameters. The acute toxicity of leachate before and after treatment fine bubble was 14.516 ppm and 11.178 ppm. The acute toxicity of leachate is considered almost non-toxic.

Abstract: Dissolved oxygen in water is one of the factors affecting plant growth in the hydroponic nutrient film technique system. The fine bubble generator technique allows the provision of high dissolved oxygen levels in water with fine bubble size and prolonged water existence. The experiment was conducted to observe the effect of fine bubbles on choy sum plant growth. Plant growth parameters including leaf length (Pd), leaf width (Ld), plant height (Tt), number of leaves (Jd), and root weight (Ba) were measured every two days while the total plant weight was measured at harvest. Nutritional water quality and microclimate were controlled using internet of things (IoT) based sensors every 5 minutes. The research data were processed using descriptive analysis. The results showed that the use of fine bubbles increased the electrical conductivity (EC), pH, and total dissolved solids (TDS). On the contrary, the nutrient solution’s temperature increased, thus reducing the total dissolved oxygen content. The yields showed that the choy sum plant growth using fine bubbles application weighed 1.71 kg (5 samples) better than the control 1.35 kg.

Abstract: Prestressed concrete ties could develop end-splitting cracks along tendons due to lateral bursting stresses. The lateral bursting stresses can form due to Hoyer effect (change in diameter of the prestressing tendons due to Poisson’s ratio), the jacking force in the tendons, geometrical features and indent characteristics of the prestressing tendons. End-splitting cracks can occur immediately after de-tensioning procedure in some cases, but they also can be developed during the first weeks after de-tensioning procedure due to sustained lateral stresses exerted by the prestressing tendons. The ability of concrete to resist these bursting stresses without cracking is primarily the function of the thickness of concrete cover, the type of concrete mixture used and the maximum compressive strength of the concrete. Qualification test will be great tool for prestressed concrete tie manufacturers to identify tie designs that may be susceptible to end-splitting cracks. This test was formally adopted as section 4.2.4 in Chapter 30 of the 2021 AREMA Manual for Railway Engineering.

Abstract: Optimization of a flatness error inspection activity on coordinate measuring machine (CMM) is a very crucial problem which demands minimization of a probe path for productive inspection. In the present work, the approach is explained to minimize the total probe travelling length and hence, the time of flatness inspection. Three sampling methods with eight sample sizes have been considered for this work. The ant colony optimization (ACO) algorithm based on travelling salesman problem (TSP) approach was developed in MATLAB environment to find the shortest probe paths. It was verified that the probe path depends on the sampling method used to measure the flatness. The sampling method giving the shortest probe path was selected as the best-suited method for a particular sample size. The results obtained by analyzing an illustrative example shows that the proposed approach is both effective and optimum.

Abstract: Today, the share of global energy mix related to renewable energy technologies is rising drastically. The main reason behind this new trend is associated with many global challenges. Sustainable development, climate change and the need for alternative sources of energy are some of the driving forces and also reason’s powering technological innovation in energy sector. However, in order to achieve climate change goals, technological advancements of green energy must be accelerated. In this paper, a grid connected three phase photo-voltaic power supply system using integral state feedback control and state observer has been examined and proposed. Mathematical modeling of main components of the PV system including the power grids, solar panels, DC-DC converter and DC-AC inverter are performed. In addition, in order to increase the efficiency of the proposed system a maximum power point tracking algorithm using fuzzy logic control is introduced. Finally, simulation results using MATLAB shows the effectiveness of the proposed solution. Keyword: PV system, green energy, DC-DC converter, DC-AC converter, Maximum power point tracking.

Abstract: Technical concerns about micro-grid dynamics, particularly in autonomous (island) mode necessitate revision of current paradigms in control of energy systems. Advanced control techniques are imperative segments for micro-grid realization. In general, micro-grids and the integration of distributed energy resources (DER) units introduce a number of operational challenges that required to be addressed in the control design and protection systems such that the reliability and stability levels are not affected significantly and subsequently ensured that the distributed generations (DGs) potential benefits are wholly harnessed. In this paper, the micro-grid coordination strategy was investigated by simply analysing the present micro-grid situation and various control strategies. More so, active-reactive power (P/Q) and droop controller based on proportional-integral (PI) and model predictive control (MPC) were designed to control the inverter output of the micro-sources. A micro-grid model, which has two photovoltaic (PV) and one wind turbine (WT) blocks, were built in MATLAB/Simulink to simulate the following three cases in this study. The three cases are as follows, the switching of operation mode between the grid connected and islanded mode, increasing and decreasing of loads in islanded mode and the disconnection of one PV system at a certain time in islanded mode. Therefore, through the simulation analyses, the MPC controller utilized in this micro-grid as compared to the PI controller, achieved desirable efficiency of the inverter’s power control and shared the load power effectively.