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Journal of Engineering and Technological Sciences
Published by Institut Teknologi Bandung
ISSN : 23385502     EISSN : 23375779     DOI : 10.5614/j.eng.technol.sci
Core Subject : Engineering,
Aerospace Engineering Automotive Engineering Chemical Engineering, Chemistry & Bioengineering Civil Engineering, Building, Construction & Architecture Electrical & Electronics Engineering
ournal of Engineering and Technological Sciences welcomes full research articles in: General Engineering Earth-Surface Processes Materials Science Environmental Science Mechanical Engineering Chemical Engineering Civil and Structural Engineering Authors are invited to submit articles that have not been published previously and are not under consideration elsewhere.
Arjuna Subject : Teknik (semua kategori) - Teknik (Lain-Lain)
Articles 185 Documents
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A Comparative Study of Carbon Surface Modification Routes: Gamma Irradiation and Aqueous Oxidation using H2O2 for Advanced Carbon/MnO2 Nanocomposite Supercapacitor Electrode Kyla Amalia Gala; Chaidir Pratama; Imam Prasetyo; Teguh Ariyanto
Journal of Engineering and Technological Sciences Vol. 58 No. 6 (2026): Vol. 58 No. 6(2026): December
Publisher : Directorate for Research and Innovation, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2026.58.6.3

Abstract

Supercapacitors have emerged as attractive energy storage devices due to their fast charging, long cycle life, and high-power density. However, their relatively low energy density remains a challenge, requiring optimization of electrode materials, particularly by increasing oxygen functional groups to improve specific capacitance. In this study, porous carbon derived from palm kernel shells (CPKS) was modified using two methods: conventional treatment using aqueous oxidation with 15% H2O2 (CPKS-h) compared with gamma irradiation (CPKS-i). MnO₂ was subsequently incorporated into both modified carbons via vacuum-assisted wet impregnation, yielding CPKS-h/MnO₂ and CPKS-i/MnO₂ nanocomposites. The samples were characterized using N₂-sorption analysis, FTIR, XRD, SEM-EDX, and TGA. The results showed that gamma irradiation better preserved the porous structure, with only a 0.99% reduction in surface area compared to 1.30% for aqueous oxidation. Both methods also increased oxygen functional groups on the carbon surface, as confirmed by FTIR and SEM-EDX analyses. Electrochemical performance was evaluated using cyclic voltammetry in a three-electrode system. Among the samples, CPKS-i/MnO₂ exhibited the best performance, achieving a specific capacitance of 521.92 F·g⁻¹ at 5 mV·s⁻¹, along with an energy density of 104.38 Wh·kg⁻¹ and a power density of 1.57 kW·kg⁻¹, outperforming CPKS-h/MnO₂. This enhanced performance is attributed to the preserved pore structure and improved surface chemistry induced by gamma irradiation, which enabled more uniform MnO₂ dispersion and promoted a synergistic combination of EDLC and pseudocapacitive mechanisms for efficient charge storage. Thus, gamma irradiation–based carbon modification combined with MnO₂ compositing offers a promising route for advancing supercapacitor research
Optimization of Robotic GMAW Parameters for Enhanced Quality of 3G Mild Steel Welds Muhammad Ilham Sukor; Hafiz Ghazali; Muhammad Mohamed Salleh; Mohd Shukri Mokhtar; Abdul Hamid; Agung Setyo Darmawan
Journal of Engineering and Technological Sciences Vol. 58 No. 6 (2026): Vol. 58 No. 6(2026): December
Publisher : Directorate for Research and Innovation, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2026.58.6.8

Abstract

With the increasing adoption of robotic welding systems in industrial manufacturing, understanding the precise control of welding parameters in this difficult position has become essential to ensuring consistent welding quality. This study focuses on evaluating the effects of key Robotic Gas Metal Arc Welding (GMAW) parameters namely current, voltage, and wire feed rate on weld bead appearance, root penetration, and tensile strength when applied to mild steel plates. The research aims to identify the optimal parameter combination capable of maximizing weld quality while minimizing defects, enabling more reliable robotic welding performance in the 3G position. To achieve this, the Taguchi Method was employed to design a robust and systematic experimental framework, allowing efficient parameter variation and analysis. An ABB IRB 1520ID robotic arm integrated with a Fronius TPS 320i robotic GMAW machine was used to ensure repeatability and control throughout the welding trials. A total of nine experimental specimens were produced based on an L9 orthogonal array, with each specimen subjected to visual non-destructive testing (NDT) to assess surface discontinuities and destructive testing (DT) to determine mechanical integrity. Analysis of the experimental data revealed that welding current, voltage, and wire feed rate significantly influence weld penetration and strength in the 3G position. The study identified 110 A of current, 17.9 V of voltage, and a wire feed rate of 2.7 m/min as the optimum parameter settings, achieving a superior tensile strength of 403 N/mm² and eliminating root penetration defects. Furthermore, optimal visual quality was quantified at 80 A, which yielded a 100% defect-free weld bead and root pass. Overall, the findings demonstrate that by establishing an optimized parameter window, this research contributes to improved process reliability, enhanced weld quality, and greater industrial applicability.
Stochastic–dynamic Modelling of Performance Degradation in a Grid-connected Rooftop Photovoltaic System Dani Yuniawan; Vetty Kartikasari; Rahman Arifuddin; Effendi Mohamad
Journal of Engineering and Technological Sciences Vol. 58 No. 6 (2026): Vol. 58 No. 6(2026): December
Publisher : Directorate for Research and Innovation, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2026.58.6.7

Abstract

This study investigates the effects of climatic variability and long-term module degradation on the technical performance of a 100-kWp grid-connected rooftop photovoltaic system installed on a university campus in a humid tropical climate. A 65-month observational dataset covering January 2020 to May 2025 was combined with 10,000 Monte Carlo iterations and a dynamic feedback model to estimate energy yield, performance ratio (PR), and performance degradation over a 25-year operating period. The simulated annual energy yield ranged from 111 to 129 MWh yr⁻¹ (P10–P90), with a median specific yield of approximately 1,200 kWh kWp⁻¹ yr⁻¹, while the PR remained within 0.75–0.80. A literature-informed two-stage degradation scenario—0.55% yr⁻¹ during Years 1–10 and 1.00% yr⁻¹ during Years 11–25—resulted in an estimated cumulative energy loss of 8.7% relative to the no-degradation baseline. Sobol sensitivity analysis identified the PR residual as the dominant contributor to annual energy-yield variance, followed by irradiance, temperature, and degradation. By preserving irradiance–temperature dependence through paired bootstrap resampling and incorporating time-dependent degradation, the proposed framework provides a more realistic representation of both short-term uncertainty and long-term performance decline. Applications to other humid tropical locations require site-specific inputs and independent validation.
Stress Distribution Prediction in front of the crack tip using Artificial Neural Networks: A Data-Driven Approach in Fracture Mechanics Khairul Anam; Anindito Purnowidodo; Pavan Kumar Asur Vijaya Kumar; Heinz E. Pettermann
Journal of Engineering and Technological Sciences Vol. 58 No. 6 (2026): Vol. 58 No. 6(2026): December
Publisher : Directorate for Research and Innovation, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2026.58.6.10

Abstract

Understanding the stress distribution in front of the crack tip is essential because this region experiences high stress concentration that can control crack initiation and propagation. This study proposes an artificial neural network (ANN) model as a computationally efficient surrogate model for predicting the stress distribution and stress values in front of the crack tip in a simple cracked geometry. The proposed ANN model complements conventional finite element method (FEM) analyses by enabling rapid stress prediction once the model has been trained. The results show that the ANN model can capture the general relationship between the stress intensity factor, radial distance, angular position, and crack-tip stress. However, its predictive performance strongly depends on the magnitude of the stress intensity factor. At low K values, the ANN model shows significant discrepancies in both stress values and contour visualization, and it cannot accurately reproduce the theoretical butterfly-shaped stress distribution. At higher K values, the predicted stress distribution is closer to the analytical solution, and the contour shape is more consistent. These findings indicate that the present ANN model should be regarded as a proof-of-concept surrogate model with limitations, rather than a replacement for analytical LEFM solutions or FEM analysis.
Topology Optimization: A Compact Review and Comparation on Level Set Technique Development in Single and Multi-material Loc Tan Le; Annisa Jusuf; Lavi Rizki Zuhal; Tatacipta Dirgantara
Journal of Engineering and Technological Sciences Vol. 58 No. 6 (2026): Vol. 58 No. 6(2026): December
Publisher : Directorate for Research and Innovation, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2026.58.6.5

Abstract

Lightweight structural design is being researched and applied across many fields, including mechanical engineering, aerospace, and manufacturing. Among the many methods used to reduce material weight while ensuring structural strength, topology optimization has become a common choice due to its ability to optimize single-material, multi-material, and other multi-material structures such as composites or porous materials. In this review article, a summary of recent research on variants of the Level Set-based topology optimization method and their effects on structural topology optimization is presented. Among the variations and extensions of the level set method, three approaches are highlighted in this study: Radial Basis Functions, Reaction-Diffusion Equation, and Velocity Field Level Set Method, with emphasis on computation speed, computational cost, optimizer, and volume fraction. This is a new aspect of this review, as it synthesizes quantitative results from studies to clarify the optimization capabilities of each approach. This optimization capability will influence more complex studies, such as multi-material optimization. Furthermore, this study compares the three selected approaches on the same system using open-source code for education to complete previously unpublished results, thereby clarifying the advantages and disadvantages of each approach in greater detail. From this, this review provides clear reasons for new studies to develop methods for more complex computational domains

Page 19 of 19 | Total Record : 185

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