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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 132 Documents
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Performance Analysis of Radiation Detection Devices in Elevated Natural Radiation Zones: A Case Study of Mamuju Regency, West Sulawesi Indonesia Abdullah, Adi Rahmansyah Amir; Permana, Sidik; Srigutomo, Wahyu; Maulana, Alan; Seno, Haryo; Purnama, Dikdik Sidik; Tursinah, Rasito; Humolungo, Ismail; Zulfahmi, Zulfahmi
Journal of Engineering and Technological Sciences Vol. 57 No. 1 (2025): Vol. 57 No. 1 (2025): February
Publisher : Directorate for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2025.57.1.8

Abstract

Three radiation detection tools were employed to assess natural radiation levels in Mamuju Regency, West Sulawesi, Indonesia. These tools comprised the NaI(Tl) Scintillator, the Geiger Muller Counter (GMC), and the Electronic Personal Dosimeter (EPD). The NaI(Tl) Scintillator and GMC measured ambient dose equivalent (H*(10)), while the EPD exclusively gauged personal dose equivalent (Hp(10)). A total of 75 measuring points were designated for assessment. Results from H*(10) measurements indicated that the GMC recorded an average H*(10) 41% higher than that of the NaI(Tl) Scintillator, with specific rates of 0.769 µSv/h and 0.457 µSv/h, respectively. Both instruments exhibited proficiency in detecting elevated levels of radiation. Discrepancies in the outcomes were attributed to differences in detector type and efficiency. The GMC, equipped with an energy-compensated detector, demonstrated enhanced efficiency compared to the NaI(Tl) Scintillator, particularly when subjected to high energy flux radiation. Anomalies emerged in the Hp(10) measurements, which surpassed the H*(10) measurements. This difference is due to the EPD's use of a conventional GM detector, which is capable of detecting gamma, beta, and X-ray radiation
The Effect of Chain Tacticity on the Thermal Conductivity of Isotactic and Syndiotactic Polystyrene Taha, Dalmn Y.; Ahmed, Israa Z.; Mohammed, Tawfeeq
Journal of Engineering and Technological Sciences Vol. 57 No. 1 (2025): Vol. 57 No. 1 (2025): February
Publisher : Directorate for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2025.57.1.7

Abstract

This study looks into the influence of tacticity on the heat conduction through isotactic and syndiotactic polystyrene. The experimental work includes the collection of five different batches of polystyrene pellets with different tacticity. The molecular weight, isotacticity index and coefficient of thermal conductance were measured using gel permeation chromatography (GPC), nuclear magnetic resonance (NMR) and thermal conductivity apparatus, respectively. The results have indicated that there are relationships between these parameters for certain conditions. The obtained data show that isotacticity index enhanced by increasing the molecular weight of polystyrene. Subsequently, the isotacticity index affected the value of thermal conductivity of polystyrene. It was observed that the decrease of isotacticity in the syndiotactic polystyrene leads to reduce its thermal conductivity by 15-20%. But, the thermal conductivity of syndiotactic polystyrene is still higher than that of isotactic mode by 30-40% in average. The NMR analysis shows that the presence of random phenyl groups in the polymer decreases its isotacticity
Innovative Approach to Graphene Film Synthesis: Factorial Design in PECVD Experiments Pitjamit, Siwasit; Vichiansan, Norrapon; Leksakul, Komgrit
Journal of Engineering and Technological Sciences Vol. 57 No. 1 (2025): Vol. 57 No. 1 (2025): February
Publisher : Directorate for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2025.57.1.6

Abstract

Graphene, a two-dimensional carbon allotrope, has garnered significant interest due to its exceptional properties and diverse applications. This study investigates the optimization of graphene synthesis parameters using plasma-enhanced chemical vapor deposition (PECVD) to enhance film properties and broaden their application potentials. Using a comprehensive factorial design approach, factors including electric power (ranging from 60 to 100 W), the acetylene-to-hydrogen ratio (ranging from 30:70 to 50:50), and discharge time (ranging from 10 to 30 minutes) were systematically varied, and film thickness and the D/G ratio served as response variables. The experimental results revealed the significant effects of these parameters on film thickness, with optimal conditions identified as an electric power of 100 W, an acetylene-to-hydrogen ratio of 50:50, and a discharge time of 10 min. The average film thickness ranged from 41.51 to 253.80 nm. Morphological and structural analyses using atomic force microscopy and Raman spectroscopy elucidated the impact of synthesis parameters on film characteristics, with the D/G ratio varying from 0.75 to 1.8, indicating the degree of graphitization and defect density. Furthermore, surface properties and wettability were assessed using contact angle measurements, providing insights into surface interactions crucial for various applications. This study culminates in discussions on the implications for graphene synthesis optimization and its potential applications across diverse fields. Overall, this research contributes to advancing the understanding of graphene synthesis methodologies and underscores its significance in driving technological innovations.
Quantitative Analysis of Gravity Currents Using the Light Attenuation Technique Tjung, Ezra Yoanes Setiasabda; Kikkert, Gustaaf Adriaan
Journal of Engineering and Technological Sciences Vol. 57 No. 1 (2025): Vol. 57 No. 1 (2025): February
Publisher : Directorate for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2025.57.1.9

Abstract

It is well known that when two fluids with different specific densities are put adjacent to each other, there is an unbalanced horizontal density gradient that results in the adjustment process to achieve equilibrium, so that the less dense fluid finds its way atop the denser fluid. The purpose of this study is to employ light attenuation technique to obtain quantitative data in investigating the mentioned phenomenon. Specifically, the gravity current experiment models what is commonly found in estuaries, where there is an unbalanced density gradient due to the different densities of saltwater and fresh water. The use of light attenuation technique enables a more accurate quantitative data collection and thus enables a more rigorous definition of the location of the nose and the thickness of the head to be applied during the analysis of experimental data. It also allows for investigating the mixing characteristics of the two fluids in the highly turbulent layer immediately behind the current head process such as the velocity and the thickness of the shear layer
Investigation of Reaction Dynamics of Methane Reforming on Nickel Clusters Using Molecular Dynamics Simulations Arifin, Rizal; Muzakki, Fikrun Najib; Winardi, Yoyok; Widaningrum, Ida; Zulkarnain, Zulkarnain; Abdurrouf, Abdurrouf; Johari, Norhasnidawani; Lee, Vannajan Sanghiran; Darminto, Darminto
Journal of Engineering and Technological Sciences Vol. 57 No. 1 (2025): Vol. 57 No. 1 (2025): February
Publisher : Directorate for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2025.57.1.5

Abstract

This study employed molecular dynamics simulations utilizing the ReaxFF force field to elucidate the mechanisms underlying methane decomposition and hydrogen generation on nickel clusters (Ni37, Ni55, and Ni80). The transformation of methane into valuable products, including carbon species and hydrogen molecules, is of considerable significance owing to the abundance of methane and its potential role as an atmospheric pollutant. The findings suggest that Ni37 clusters had the highest initial reactivity, although they deactivated swiftly; conversely, Ni55 and Ni80 exhibited more consistent reaction rates. The highest efficiency of hydrogen production per unit surface area was displayed by Ni55 clusters within 100,000 fs, demonstrating a balance between reactivity and stability. Methane dissociation on the Ni55 clusters occurred in multiple stages. Two distinct mechanisms for hydrogen formation were identified: simultaneous dissociation from methane and migration and the combination of hydrogen atoms on the cluster surface. Ni55 showed a substantially lower activation energy for methane dissociation at 0.5 eV than bulk nickel, suggesting a higher degree of reactivity. Conversely, the activation energy for hydrogen formation was 1.1 eV. These results highlight the potential of the Ni55 clusters as effective catalysts for hydrogen production and methane conversion
Geometrically Complex, Relatively Weak, and Subcritically Stressed Lembang Fault May Lead to a Magnitude 7.0 Earthquake Palgunadi, Kadek Hendrawan; Simanjuntak, Andrean Vesalius Hasiholan; Ry, Rexha Verdhora; Daryono, Mudrik Rahmawan; Widiyantoro, Sri; Warnana, Dwa Desa; Triahandini, Agnis; Syaifuddin, Firman; Ahmadiyah, Adhatus Solichah; Sirait, Anne Meylani Magdalena; Suryanto, Wiwit
Journal of Engineering and Technological Sciences Vol. 57 No. 1 (2025): Vol. 57 No. 1 (2025): February
Publisher : Directorate for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2025.57.1.10

Abstract

The Lembang Fault is one of the major faults in the province of West Java, approximately 10 km north of its capital, Bandung, a city inhabited by more than 2 million people. The fault exhibits distinct geometrical characteristics in its 29 km length, transitioning from normal, strike-slip, to vertical faulting mechanisms. Two studies have evidence of a normal fault with a dip direction to the north and a thrust fault with a dip direction to the south. Despite the lack of significant recorded earthquakes, the Lembang Fault is active and poses a high seismic hazard to the surrounding region. Previous deformation studies estimate that the fault could produce earthquakes of magnitude 6.7 to 7.0, though these estimates do not account for the fault's unique geometry, which includes bends at both its eastern and western ends. This geometrical complexity can significantly affect slip distribution, potentially leading to over- or underestimating earthquake magnitude. In this study, we assess the earthquake potential of the Lembang Fault using 3D dynamic rupture simulations that incorporate the fault's geometrical complexity, 3D velocity structure, and plastic deformation. Our simulations indicate that the fault's complex geometry enhances rupture slip to the east while halting it to the west, resulting in rupture along 80% of the fault's total length. However, according to our model, a self-sustained runaway rupture scenario occurs only if the fault is characterized by relatively weak apparent strength, subcritical stress, and overpressurization. This worst-case scenario could result in a magnitude 7.0 earthquake, posing a significant threat to the densely populated nearby city. Therefore, our findings have crucial implications for seismic hazard assessment around the Lembang Fault.
Exploration of Biomimetic Metal-Organic Catalysts for Splitting Glucose into Dihydroxyacetone and Glyceraldehyde Sumargo, Margaretha; Audreylia, Vanessa; Luivan, Samuel; Susanti, Maria Patrycia Della; Soerawidjaja, Tatang Hernas; Hudaya, Tedi
Journal of Engineering and Technological Sciences Vol. 57 No. 2 (2025): Vol. 57 No. 2 (2025): April
Publisher : Directorate for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2025.57.2.1

Abstract

Lactic acid is a metabolite produced during glucose glycolysis, typically generated industrially through the fermentation of glucose using microorganisms. However, the high production cost of this fermentation process makes lactic acid relatively expensive, rendering biodegradable plastics made from polylactic acid less competitive. This research focuses on the initial stages of glucose glycolysis process, in which glucose is split into dihydroxyacetone and glyceraldehyde, both of which are isomers of lactic acid. Biomimetic metal-organic catalysts composed of Mg-Zn tripolyphosphate, imidazole, and monosodium or monoammonium glutamate were tested in a water–acetonitrile reaction medium. Prior to catalyst testing, either water–acetonitrile or water–acetonitrile–acetone solutions were chosen as the reaction medium based on their effectiveness in producing phase separation. The study investigated the effects of catalyst concentrations, catalyst types, and reaction temperatures on glucose conversion, as well as the yield and selectivity of dihydroxyacetone and glyceraldehyde within 6 hours reaction time at pH 8. The results showed that these biomimetic metal-organic catalysts effectively facilitated the splitting of glucose in a water–acetonitrile solution, achieving the best glucose conversion of 57.16% at a temperature of 90°C with a catalyst concentration of 0.8%-mol.
Development of a Novel Umbilical Retraction Mechanism for a Launch Vehicle Nguyen, Manh-Cuong; Pham, Van-Tung; Nguyen, Van-Tinh; Nguyen, Duy-Hung
Journal of Engineering and Technological Sciences Vol. 57 No. 2 (2025): Vol. 57 No. 2 (2025): April
Publisher : Directorate for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2025.57.2.7

Abstract

Umbilical or umbilical cable supplies are required for an apparatus, such as a space vehicle, or for a person, a diver, or an astronaut. For launch vehicles, umbilical cables provide essential elements like electrical power, communication, and pressurized gases before liftoff. Ensuring the retraction of these cables is crucial for preventing potential damage during the launch process. This paper addresses a novel mechanism for umbilical retraction in the launch vehicle loading process. This mechanism is based only on the principles that borrow the vehicle’s launch motion to generate a cable-cutting action, and no power is required. The new design of the umbilical retraction device is optimized through simulation and validated by the experiment. The results confirm that the introduced mechanism works effectively with a maximum number of 20 umbilical cables consisting of two forms, namely PVC and metal covers.
Adaptive Ensemble Learning for Enhancing Building Energy Consumption Prediction: Insights from COVID-19 Pandemic Energy Consumption Dynamics Handre Kertha Utama, Putu; Leksono, Edi; Nashirul Haq, Irsyad; Indrapraja, Rachmadi; Mahesa Nanda, Rezky; Friansa, Koko; Fauzi Iskandar, Reza; Pradipta, Justin
Journal of Engineering and Technological Sciences Vol. 57 No. 2 (2025): Vol. 57 No. 2 (2025): April
Publisher : Directorate for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2025.57.2.2

Abstract

Buildings account for approximately 40% of the total global energy consumption. Therefore, accurate prediction of building energy consumption is necessary to optimize resource allocation and promote sustainable energy usage. A key challenge in developing building energy consumption models is their adaptability to abrupt changes in consumption patterns owing to extraordinary events, such as the COVID-19 pandemic. Therefore, a two-layer ensemble-learning (EL) model incorporating sliding windows as input features is proposed. The model is a two-layer stacking EL consisting of two base learning methods: (1) support vector regression (SVR), and (2) random forest (RF). Temperature and humidity are included to account for the influence of weather conditions on energy consumption. The proposed model is deployed to forecast building energy consumption both before (November 2019) and during (May – October 2020) the COVID-19 pandemic and is compared with a single machine learning model. The results demonstrate that the EL model outperforms the SVR and RF methods, providing excellent prediction accuracy even during the pandemic when significant changes in energy consumption patterns occurred. The findings also highlight the effectiveness of sliding windows as input features for improving model adaptability. Additionally, the analysis reveals that temperature is more prominent than humidity for improving prediction accuracy.
Practical Precooling Methods for Alleviating Heat Strain during Occupational Heat Exposure Wijayanto, Titis; Huda, Listiani Nurul; Rizalmi, Sigit Rahmat
Journal of Engineering and Technological Sciences Vol. 57 No. 2 (2025): Vol. 57 No. 2 (2025): April
Publisher : Directorate for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2025.57.2.3

Abstract

Working in hot and humid environments poses significant challenges to thermoregulation and potentially affects performance and health. Strategies for mitigating heat stress are critical for workers exposed to high thermal loads. This study investigated practical cooling strategies, that is, phase-change vest (PCV) cooling and crushed ice (ICE) ingestion, before a physical activity in a hot and humid environment to alleviate heat strain. Two experiments were conducted to evaluate the efficacy of the cooling methods: the first experiment involved participants wearing a PCV for precooling, and the second experiment involved participants consuming an ICE (7.5 g/kg body mass) before exercising under the same conditions. Physiological responses including tympanic temperature, skin temperature, and heart rate, along with perceptual measures such as thermal sensation and perceived exertion, were assessed. The results showed that both the PCV and ICE interventions effectively reduced heat strain, although they had different effects. PCV cooling effectively reduces physiological and perceptual strains immediately after physical exertion; however, this effect does not last in the recovery phase. In contrast, ICE ingestion reliably lessens physiological and perceptual strains throughout the activity and recovery periods, substantially impacting both physical strain and the perception of effort. These findings highlight the significance of ICE ingestion as an effective strategy for enhancing worker health and safety in demanding thermal environments.

Page 8 of 14 | Total Record : 132

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