This study evaluated the 4E (energy, exergy, economic, and environmental) performance of hybrid PVT–biomass furnace greenhouse solar dryers with a rotating rack for fish drying. The dryers operated under two modes: with exhaust air recirculation (GHSD-WAR) and without exhaust air recirculation (GHSD-NAR). GHSD-NAR reduced the fish mass from 86.76 kg to 34.74 kg (20% moisture content) in 9.9 h at an average drying temperature of 57.7 °C, while GHSD-WAR achieved similar drying performance, reducing the mass from 87.13 kg to 34.89 kg in 9.57 h at 58.2 °C. In terms of energy consumption, GHSD-NAR and GHSD-WAR consumed 261.25 kW and 180.51 kW, respectively. The average specific moisture extraction rate (SMER) and specific energy consumption (SEC) were 0.1525 kg/kWh and 12.039 kWh/kg, respectively, for GHSD-NAR, and 0.2253 kg/kWh and 7.689 kWh/kg, respectively, for GHSD-WAR. The average thermal efficiency and exergy efficiency were 12.39% and 74.43%, respectively, for GHSD-NAR, and 18.48% and 75.46%, respectively, for GHSD-WAR. The economic payback period and energy payback time for GHSD-NAR were 1.73 years and 1.006 years, respectively, while those for GHSD-WAR were 1.35 years and 1.007 years, respectively. Over a 10-year system lifetime, CO₂ mitigation was estimated at 156.2 tons (worth USD 4,825 in carbon credits) for GHSD-NAR and 162.6 tons (USD 5,944) for GHSD-WAR. The GHSD-WAR system achieved up to 40.77% energy savings compared to GHSD-NAR. Overall, the 4E analysis results indicated that GHSD-WAR outperformed GHSD-NAR in terms of energy efficiency, economic return, and environmental impact. These findings indicate that GHSD-WAR is potentially a more sustainable drying solution for fish processing.
Ceramic insulators on 150 kV transmission lines are prone to contamination from dust and moss, which can degrade insulation performance and increase the risk of system failure. This study aims to identify insulator contaminants using image processing techniques and Mamdani fuzzy logic integrated with an Internet of Things (IoT) platform to assess the dielectric strength of 150 kV ceramic insulators. The method involves capturing images of the insulator surface using a monocular digital microscope, applying OpenCV-based image processing for segmentation and quantification of contamination, and classifying contamination levels using Mamdani fuzzy logic. The results show that the system can accurately detect the percentage of dust and moss contamination. The processed image data are used as input to the fuzzy system to determine the dielectric strength of the insulator. Simulations demonstrate consistent classification of contamination into three levels: low, medium, and high. The system is integrated with the Ubidots IoT platform for real-time monitoring of insulator conditions. As contamination levels increase, the insulator's breakdown voltage decreases, with dust having a greater impact than moss, especially under high humidity conditions. The dielectric strength ranges from 45 kV to 110 kV, with values below 60 kV considered critical.
This study evaluates the effectiveness of epoxy-SiO2 coatings in enhancing the dielectric strength of contaminated ceramic insulators through contact angle analysis. Insulators in tropical regions, such as the 150 kV Koto Panjang-Payakumbuh line, often suffer from performance degradation due to moss contamination and high humidity, leading to reduced hydrophobicity and an increased risk of flashover. Contact angles were measured using the sessile drop method before and after coating. Uncoated insulators exhibited hydrophilic behavior with contact angles below 90° (53.81°, 72.70°, and 60.14°). Pure epoxy improved the values to 87.52°, 91.62°, and 85.94°, indicating partial hydrophobicity. The addition of SiO2 nanoparticles further increased the values above 100° (100.26°, 99.33°, and 101.33°). Based on the empirical correlation between contact angle and dielectric strength, dielectric performance improved from 124.4 kV/cm (uncoated) to 176.7 kV/cm (epoxy) and 200.4 kV/cm (epoxy-SiO2). The novelty of this work lies in demonstrating, for the first time, the comparative effectiveness of epoxy and epoxy-SiO2 coatings under real tropical contamination conditions. These findings confirm that epoxy-SiO2 coatings not only improve hydrophobicity but also provide a homogeneous protective layer, thereby reducing leakage current and strengthening dielectric endurance. The results highlight a cost-effective preventive maintenance strategy with both scientific and practical contributions for high-voltage transmission systems in tropical environments.
The permanent magnet synchronous motor (PMSM) is commonly used in industrial and home appliances for its high efficiency and dynamic performance. In this research, a PMSM drive based on field-oriented control (FOC) is designed and simulated using MATLAB/Simulink. The speed controller of the drive is tuned using the trial-and-error method. However, the method requires more time for testing and adjustment of the speed controller to generate an optimal output response. Thus, particle swarm optimization (PSO) and artificial bee colony (ABC) algorithms, which require less computational effort and effectively produce good responses, are used to optimize the speed controller of the drive. PSO and ABC also offer an attractive optimization framework because of their independent, agnostic model structures, global searching capability, and low-load real-time calculation. In this study, the results obtained from different tuning methods are compared to determine the best optimization method of the speed controller in the PMSM drive under different operations. Other than that, performance measures such as integral square error (ISE), integral absolute error (IAE), and integral time absolute error (ITAE), which are commonly used to measure the effectiveness of a controller, are also discussed. The results show that the PMSM drive based on the ITAE criterion using the ABC algorithm gives better performance under different conditions.
This study is motivated by the importance of track geometry conditions in ensuring the safety and smooth operation of railway systems, particularly in curved segments that are highly prone to deviations. The objective of this research is to evaluate the safety level of track geometry at Curve No. 5, Km 2+340 to Km 2+494, located between Padang Station and Pulau Air Station, and to formulate maintenance recommendations based on the Level of Safety (LOS) in accordance with the technical guidelines of the Directorate General of Railways. The research methodology includes field observations, measurement of geometric parameters, analysis of compliance with technical standards, and classification of safety levels. The evaluation is conducted at the existing operating speed of 20 km/h and the planned speed of 40 km/h in accordance with the 2025 Train Travel Diagram (Gapeka 2025). The results indicate that the track remains suitable for operation at LOS 1–2 with the need for preventive maintenance. However, at the planned speed, the safety level increases to LOS 3–4 due to the highest deviation found in rail cant. Overall, the track is safe for operation, and speed increases should only be implemented after compliance with the required standards is achieved.
