Advanced Engineering Forum Vol. 51

Abstract: Electrospinning is a cost-effective and versatile technique to fabricate continuous fibers ranging from submicron diameter to nanometer diameter. Polybutylene adipate-co-terephthalate (PBAT) has been investigated as a fibrous scaffold because of its low crystallinity, rapid biodegradability, and excellent mechanical properties, particularly for its high toughness and flexibility. However, the potential of the PBAT fibrous scaffold for medical purposes is still limited. PBAT blends with biocompatible polymers have been developed and investigated for tissue engineering applications. Herein, the preliminary research examines the processability of neat PBAT as a fibrous scaffold by varying several electrospinning processing parameters, such as solution concentration, voltage, flow rate, and tip to collector distance. The aim is to obtain continuous, smooth, and bead-free fibers. The electrospun fibers were examined using a scanning electron microscope (SEM) to determine its diameters. The optimum parameters for obtaining a continuous, bead-free PBAT fibrous scaffold were 20% w/v concentration, 19 kV voltage, 2 mL/h flow rate, and a 15 cm distance.

Abstract: With increasing concerns regarding plastic waste and pollution, researchers have been looking to develop advanced materials from biodegradable plastics. This study features a halochromic biodegradable polymer produced using additive manufacturing. The purpose of this research is to fabricate halochromic polylactic acid (PLA) filaments and assess its halochromic behaviour, mechanical and chemical properties of the 3D printed PLA specimens. PLA/polyethylene glycol (PEG)/bromocresol purple (BCP) compound was prepared and added in extrusion to produce a 3D printing filament. Dumbbell-shaped and rectangular specimens were fabricated from the filament through 3D printing. The halochromic responsiveness and colour reversibility were tested by exposing the samples to liquid and vaporized hydrochloric acid (strong acid), acetic acid (weak acid) and ammonia (strong alkali). The tensile properties, fracture surface morphology and chemical species of the specimens were tested and analyzed through tensile test, scanning electron microscopy (SEM) and Fourier Transform Infrared (FTIR) spectroscopy. The halochromic responsiveness shows obvious colour changes from yellow to blue when exposed to strong alkali. The tensile strength and modulus were found to be higher in comparison to plasticized PLA but the elongation at break was lower. SEM morphology show brittle fracture characteristics in the printed specimens. Overall, the 3D printed halochromic PLA specimens show promising results and have proven their functionality as pH sensors which offers wide applications in many industries such as medical, environmental and packaging.

Abstract: Most of the coal mining in Indonesia that uses the open pit mining method faces serious problems, namely the treatment of acid mine drainage. This constitutes a relatively large volume of wastewater, especially in areas that have rainfall in the range of 2000–4000 mm yearly. Acid mine drainage as acidic wastewater formed during excavation cannot be avoided due to the oxidation process during overburden removal. The acidic wastewater that has formed must be managed strictly and appropriately prior to being released into public waters. There are two methods of treating acid mine wastewater, namely active and passive treatments. Active treatment is generally used more frequently during operations, considering the time, effort, and costs; however, when entering the mine closure period, natural processes must be used at lower costs. Undertaking passive treatment in this area has shown a reduction in the chemical materials used and has enabled a greater amount of wastewater to be managed. The purpose of this research is to describe the active and passive treatment processes in the management of acid mine drainage and to analyze the results of passive treatment in preparation for the mine closure stage. Development of passive treatment by swampy forest system can reduce cost of treatment, naturally process and more environment friendlier by reducing the quicklime materials.

Abstract: This paper presents a case study of solar drying of hydroxide sludge in the region of Marrakesh, Morocco. The experiments of solar greenhouse drying processes of the hydroxide sludge were studied in summer and winter seasons. The representative samples were in three volumes. The greenhouse sludge dryer was designed and constructed as a horticultural plant. Results showed that the dry of the three samples was reached in only 13 hours in summer and 25 hours in winter. The time of solar greenhouse drying registered was significantly lower compared to several studies. The higher values of drying rate were obtained in early hours of experiments in summer. The maximum ranges obtained were 0.25 kg water/kgDS.h for the hot season and 0.020 kg water/kgDS.h for the cold season. The important influence of the temperature had a greater effect with wind speed on drying rate. The sludge water evaporation caused a large volume reduction with a shrinkage during the processes in both seasons.

Abstract: The development of road and highway networks sometimes involves passing through compressible soils of poor quality. Given their mechanical properties as foundation soils, these soils are characterized by low short-term shear strength, expressed by undrained cohesion, which increases during soil consolidation, and are also characterized by significant compressibility, resulting in large-scale settlements when a load is applied to them. Nowadays, there are reinforcement methods that make it possible to execute these structures while limiting the risks of instability. This study consists of the numerical analysis of a light-weight embankment of a highway section built on soft soils. Two reinforcement methods are investigated to support the embankment layers and reduce settlement. Interest is given to the behavior of the soils in place before and after the installation of the adopted reinforcement. The analysis is carried out in such a way as to show the importance of the complete consolidation of the soils in place in the long term, which makes it possible to take into account the dissipation of the pore pressures.

Abstract: This paper investigated the behavior of a DSTATCOM in the face of contingencies that may arise in an electrical power distribution network. It shows that DSTATCOM is an effective attenuator to limit the impacts of perturbations on the distribution network. The model equations are simulated in a MATLAB environment and have shown that the exactitude of the network parameters is a key determinant of the resilience of a disrupted distribution network in the presence of an optimally positioned DSTATCOM at a node. The capacitive current of the DSTATCOM increases inversely with a bad power factor and a critical voltage drop. The DSTATCOM in a network is therefore more solicited when the operating parameters of this network degrade as a result of single-phase or multiphase short circuits. Distribution system operators must therefore design protection plans that truly and sustainably limit the impacts of short circuits on distribution systems.

Abstract: This work addresses the challenges associated with the development of short neutral sections (SNS) for overhead lines of high-speed moving trains. A crucial function of a short neutral section is to provide electrical isolation between the different phases of AC traction. These sections are typically located in proximity to the traction substation and sectioning posts. The current SNS design presents several issues, including pantograph arcing, wear and tear of the overhead line system, and the need for manual rotation during periodic maintenance. To address these challenges TRIZ is used, a problem-solving methodology that leverages inventive principles to generate innovative solutions. The work outlines the use of several TRIZ tools and techniques, including the Interaction Matrix, Functional Analysis, Function-Body Diagram (FBD), Trimming, and the Contradiction Matrix [1]. With the application of these tools, the author presents several potential solutions for improving the SNS design to eliminate periodic maintenance and services. One proposed solution involves the use of a segmented overhead line system with an insulating cylinder-shaped discrete insulator to ensure smooth contact of the pantograph. Another solution involves the use of a twisted strip-based insulator to replace linear motion with rotating movement, eliminating the need for manual rotation. The work emphasizes the importance of considering various factors, such as design, material, wear rate, maintenance, and creepage distance, when evaluating the feasibility of these solutions. By leveraging TRIZ to generate innovative solutions, the author demonstrates the potential of this methodology to drive innovation and overcome complex challenges in the development of short neutral sections for high-speed rails.

Abstract: This investigation presents an experimental study on the performance, specific fuel consumption, and exhaust emissions of a 14-kW diesel engine generator fueled with neat cottonseed biodiesel and biodiesel/diesel blends. Cotton biodiesel was chosen due to its importance as an agricultural crop and potential as a biodiesel feedstock. The fuels tested were (B100 - pure cotton biodiesel), (B7 - 7% biodiesel, 93% Petro diesel), (B20 - 20% biodiesel), (B30 -30% biodiesel), (B50 - 50% biodiesel), and (B70 - 70% biodiesel). The generator was tested at various loads from 0-14 kW. Properties like viscosity, density, and calorific value were measured for each fuel. The results showed that brake thermal efficiency increased with load for all fuels but was lower for higher biodiesel blends. Exhaust gas temperature followed a similar trend. Specific fuel consumption increased with biodiesel content, attributed to the lower energy density of Biodiesel. B100 had the highest NOx emissions but the lowest carbon monoxide and smoke emissions. The study concludes that cottonseed biodiesel and blends can replace Petro diesel in diesel generators. Increasing biodiesel content causes slight reductions in performance but improvements in emissions. The results provide insights into using cotton biodiesel in engines and generators.