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Ethylene Evaporation Rate Analysis in the Storage Tank and Boil-Off Gas Dispersion: Case Study in PT Lotte Chemical Titan Nusantara
Full text linkAs a primary raw material at PT Lotte Chemical Titan Nusantara (LCTN), ethylene storage is 12,000 tons in icy conditions (- 103.6 °C and 40-80 mbarg) before processing into polyethylene. Ethylene evaporation is inevitable. Therefore, the proper handled of ethylene needs to be settled. The evaporation rate or Boil-Off Rate (BOR) of ethylene is predicted to be 0.0705-0.0730% vol/day, and the Boil-Off Gas (BOG) is 9.41-9.76 tons per day (at 21-40 °C and a tank liquid level of 15.41 meters, approx. 52.51% volume of tank). The BOR is a predicted value of the percentage of volume evaporated daily. When the liquid level is increased, the BOR rate will also be increased. The size of any leaks dramatically impacts the gas dispersion radius. A leak with a 10 mm size at wind speeds of 5 and 10 km/hr resulted in the radius distance of BOG dispersion being 8.2 and 7.7 m, respectively. When the leak hole is ten times bigger, ca. 100 mm, the radius is eight times wider. Fortunately, gas releases happen well above ground level (15.5 meters), causing the cloud to rise, keeping personnel safe. Too low liquid levels ramp up evaporation, risking shortages, while overfilling increases BOG, raising the chance of spills and safety hazards. Hence, managing these variables is crucial to keep operations smooth and safe
SUSTAINABLE ARCHITECTURE RESEARCH TRENDS: A BIBLIOMETRIC ANALYSIS FOCUSING ON BUILDING FAÇADE DESIGN WITH THE INFLUENCE OF THERMAL COMFORT
Full text linkBuildings account for a significant portion of global energy use, making facade design a critical component in efforts to achieve sustainable architecture. In tropical climates, challenges such as high solar radiation, temperature, and humidity increase the demand for innovative facade strategies that improve thermal comfort and energy efficiency. Proven strategies such as shading devices, roof overhangs, and natural ventilation have demonstrated effectiveness in reducing indoor heat gain and increasing occupant comfort. This study aims to analyze current research trends in sustainable architecture with a focus on building facade design and its impact on thermal comfort. Bibliometric analysis was carried out using Scopus-indexed publications from 2016 to 2025, with keywords related to building design, thermal comfort, and facade efficiency. VOSViewer software was used to map keyword networks, visualize publication trends, and identify dominant themes and research clusters. The analysis includes 51 relevant publications and reveals a growing interest in facade-related energy research over the last decade. The majority of research is focused on engineering, energy, and environmental science, with global contributions from China, the United States, and Italy. Keyword clustering identified three core research themes: architectural design strategies, building envelope technologies, and thermal comfort performance. Despite a growing body of research, this study highlights a gap in facade design research specifically adapted to tropical climates, where humidity and solar radiation issues require more context-sensitive solutions. These findings underscore the need for more localized and multidisciplinary research, as well as the integration of adaptive and intelligent façade systems. This research contributes to the knowledge base by identifying research patterns and gaps, offering a foundation for future investigations into facade innovations that support energy-efficient and thermally comfortable buildings in diverse climate contexts
Comparison of Flood Hydrograph of Manikin Dam Watershed Using Synthetic Unit Hydrograph Method, HEC-HMS and Rain on Grid Model with HEC-RAS 2D
Full text linkManikin watershed is located in Kuaklalo Village which borders Bokong Village, Taebenu Subdistrict, Kupang Regency, East Nusa Tenggara Province which has an area of 49.31 km2 with a river length of 8.62 km which has a semi-arid climate with a fairly high annual rainfall of around 1000 - 1500 mm. This study aims to compare the design flood discharge and peak hour with Nakayasu Synthetic Unit Hydrograph (HSS) method, GAMA I, HEC-HMS and rainfall discharge model with HEC_RAS 2D in Manikin Dam watershed. In this study, 6-hour rainfall with a return period of 50 years and 100 years was used. Based on the analysis results, the calculation of the hydrological numerical model flood discharge with the HEC-HMS method with a return period of 50 years and 100 years is 511.90 m³/s and 599.30 m³/s with a peak time at the 4th hour. The peak discharge values obtained using the Nakayasu Synthetic Unit Hydrograph and GAMA I methods with a return period of 50 years and 100 years are 342.11 m³/s, 381.14 m³/s and 406.44 m³/s, 456.13 m³/s, and the peak time obtained at SUH Nakayasu is 3 hours and GAMA I is 4 hours. Numerical model results with HEC-RAS 2D v6.6 with 6 hours of rainfall on the grid obtained peak discharge hydrograph values for the 50-year and 100-year return periods of 494.86 m³/s and 604.88 m³/s, with the peak time at the 5th hour. Therefore, the largest peak discharge and peak time results were obtained from the HEC-HMS method among the three SUH formulas and HEC-RAS calculations
An Experimental Study of Stagger Angle Effect Placed in front of Returning Side toward the Savonius Wind Performance Using Overlap Myring Blade for n = 1
Full text linkThe previous Savonius wind turbine studies have proved that overlap modifications to conventional blades can improve turbine performance. With these conventional blades, the performance is less optimum because the drag force generated by turbine's rotation is still high. Based on this condition, this experiment is conducted by modifying Savonius wind turbine with overlap blades using Myring equation n = 1. Its blade profile is made half-elliptical to reduce drag force. Diameter and height of the turbine are 400 mm with 0.3 overlap ratio. The ratio of cylinder diameter (ds/D) is 0.4, and the ratio of cylinder center distance (S/d) is 1.7. Experiments are conducted by varying stagger angles of circular cylinder in front of returning blade are 45°, 50°, 55°, and 60° with velocity 5 m/s. The final results show that the best performance improvement of the turbine occurs at 60° stagger angle. The increase in torque coefficient is 4.95% and power coefficient is 20.16% to overlap Savonius wind turbine with myring n = 1 with no circular cylinder
Load Cell Failure Risk in Tandem Mobile Crane Lifting: A Fuzzy Fault Tree Analysis Approach
Full text linkLoad cell is an critical component in the tandem lifting system using a mobile crane that functions to measure the load accurately. Damage to the load cell can cause operational failure and increase the risk of accidents. This study aims to analyze the potential for load cell damage using the Fuzzy Fault Tree Analysis (FFTA) approach. FFTA combines fault tree logic with fuzzy theory to clarify risk assessment. By collecting data from study literature, interviews and historical equipment data, the analysis results obtained that the factors causing load cell damage include overload factors, damage factors to load cell components and environmental factors. And through the FFTA method, namely the damage factor to the load cell component with a weighting value of 0.1840 or 47%. The contribution of this study is to provide a systematic approach to identifying and evaluating the risk of load cell damage, which can be used as a basis for improving inspection programs and preventive maintenance on tandem lifting using a mobile crane. This approach can also support management decision making in improving the reliability and safety of lifting equipment
Investigation of Planing Hull Resistance Calculation Using Smoothed Particle Hydrodynamics
Full text linkOver the decades, advancements in computer technology have significantly contributed to the development of numerical methods, including computational fluid dynamics (CFD). CFD encompasses two primary approaches: mesh-based and mesh-free methods. While mesh-based methods are well-established and widely used for analyzing free-surface flows, such as ship resistance, mesh-free methods like smoothed particle hydrodynamics (SPH) have gained traction in real-world engineering applications. Despite its growing use, limited research has explored the application of SPH to ship resistance analysis. This study investigates the total ship resistance of a planing hull using the open-source SPH solver DualSPHysics. The research focuses on analyzing spray patterns and complex flow dynamics around the hull. DualSPHysics typically employs dynamic boundary conditions (DBC) as its standard boundary definition method. However, this study utilizes an advanced implementation of DBC, known as Modified Dynamic Boundary Conditions (mDBC), in conjunction with Project Chrono for enhanced simulation accuracy. The results demonstrate that SPH provides acceptable accuracy when compared to the Strip theory approach. Additionally, key parameters such as total force, sinkage, and trim are effectively reproduced using Project Chrono. This research highlights the potential of SPH, particularly with advanced boundary conditions, for ship resistance analysis and contributes to the growing body of knowledge in this field
Performance of a Savonius Turbine with Circular Cylinders Installed in Front of the Convex Blade and Next to the Concave Blade
Full text linkEnergy demand is found to be increasing alongside population growth. With fossil energy resources depleting, the necessity for utilizing renewable energy sources, such as wind energy, is recognized. The Savonius wind turbine, characterized by simple construction and the ability to operate at low angular speeds, is noted for its poor efficiency. Circular cylinders were installed to evaluate their impact on turbine performance. Experiments were conducted using two configurations. In the first configuration, a circular cylinder was placed beside the concave blade. In the second configuration, circular cylinders were installed next to the concave blade and in front of the convex blade. Circular cylinders with a diameter of 0.5 times that of the turbine blade were utilized. Wind speeds were varied at 4, 5, 6, and 7 m/s. The coefficients of moment, power, and static torque were obtained. Analysis indicated that the addition of the cylinders in both configurations did not significantly enhance the coefficients of power and moment, but did improve the turbine's ability to self-start. For the turbine with the circular cylinder installed, increasing wind speed resulted in decreasing relative performance compared to the conventional turbine
Modeling and Estimating GARCH-X and Realized GARCH Using ARWM and GRG Methods
Full text linkThis study evaluates the fitting performance of GARCH-X(1,1) and RealGARCH(1,1) models, which are extensions of GARCH(1,1) model by adding the Realized Kernel measure as an exogenous component, on real data, namely the Financial Times Stock Exchange 100 and Hang Seng stock indices over the period from January 2000 to December 2017. The models assume that the return error follows Normal and Student-t distributions. The parameters of models are estimated by using the Adaptive Random Walk Metropolis (ARWM) method implemented in Matlab and the Generalized Reduced Gradient (GRG) method. The comparison of estimation results shows that the GRG method has a good ability to estimate the models because it provides the estimation results that are close to the results of the ARWM method in terms of relative error. On the basis of Akaike Information Criterion, the RealGARCH models perform better than the GARCH-X models, where the RealGARCH model with Student-t distribution provides the best fit
Analisis Faktor-Faktor Behavioral Intention Mahasiswa menggunakan Kendaraan Listrik dengan Pendekatan Extending The Unified Theory Of Acceptance And Use Of Technology 2 (UTAUT2)
Full text linkThe purpose of this study is to determine the factors that influence students towards Behavioral Intention or adoption of EV technology. Poor air quality caused by high transportation activities and exhaust emissions is an environmental problem faced by D.I Yogyakarta. The reason is the increase in educational potential which resulted in the number of students increasing by 0.97% from the previous year. Electric Vehicles (EVs) represent one of the solutions to this issue. Data collection by distributing questionnaires to 400 respondents at a confidence level of 95% using a disproportionate stratified random sampling technique. The model and theory approach used is the Unified Theory of Acceptance and Use of Technology2 (UTAUT2). The analysis results indicate that out of the 7 variables examined, several play a significant role in influencing students' behavioral intentions toward using electric vehicles, there are 4 significant variables, namely Performance Expectancy, Facilitating conditions, Hedonic motivation and Habits
Uji Karakteristik Tanah Kohesif Pada Kawasan Perumahan Dwifa Residence Kota Bengkulu dan Implementasinya untuk Perencanaan Pondasi Dangkal Berdasarkan Metode Elemen Hingga
Full text linkPenelitian ini dilakukan untuk mengindentifikasi karakteristik tanah kohesif pada kawasan Perumahan Dwifa Residence Kota Bengkulu, dan pengaplikasiannya pada desain struktur pondasi dangkal tipe telapak. Pengujian diawali dengan uji sifat fisis, yaitu uji kadar air, berat volume, berat jenis, analisis ukuran butir, danatterberg limits, dari pengujian tersebut diklasifikasikan tanah pada lokasi ini merupakan tanah lanau elastis (MH). Pengujian sifat mekanis, meliputi uji kuat tekan bebas, dan konsolidasi. Pemodelan pondasi dilakukan dari data hasil uji sifat fisis dan mekanis tanah berbasis aplikasi berdasarkan metode elemen hingga di salah satu titik, dengan nilai kuat tekan bebas (qu) dan kuat geser (Su) terkecil dari ketiga titik lokasi penelitian, untuk kedalaman 0,5 m, 0,75 m, dan 1 m beserta variasi lebarnya, agar lebih konservatif. Nilai faktor aman terkecil diperoleh 1,856 dan terbesar 6,632, dengan nilai beban vertikal maksimum terbesar 173 kN/m2 untuk kedalaman 1 m dan lebar pondasi 2 m