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All Journal Automotive Experiences Makara Journal of Technology Humanitas: Indonesian Psychological Journal Prosiding SNTTM Journal Of Biology Education Research (JBER) Scientific Contributions Oil and Gas
Harinaldi .
Department Of Mechanical Engineering, Faculty Of Engineering, Universitas Indonesia, Depok 16424, Indonesia
Religion Aerospace Engineering Agriculture, Biological Sciences & Forestry Humanities Automotive Engineering Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Civil Engineering, Building, Construction & Architecture Control & Systems Engineering Education Electrical & Electronics Engineering Energy Engineering Environmental Science Health Professions Immunology & microbiology Industrial & Manufacturing Engineering Materials Science & Nanotechnology Mechanical Engineering Social Sciences Other

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Modification of Flow Structure Over a Van Model By Suction Flow Control to Reduce Aerodynamics Drag Harinaldi, Harinaldi; Budiarso, Budiarso; Warjito, Warjito; Kosasih, Engkos Achmad; Tarakka, Rustan; Simanungkalit, Sabar Pangihutan; Lay Teryanto, I Gusti Made Fredy
Makara Journal of Technology Vol. 16, No. 1
Publisher : UI Scholars Hub

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

Automobile aerodynamic studies are typically undertaken to improve safety and increase fuel efficiency as well as to find new innovation in automobile technology to deal with the problem of energy crisis and global warming. Some car companies have the objective to develop control solutions that enable to reduce the aerodynamic drag of vehicle and significant modification progress is still possible by reducing the mass, rolling friction or aerodynamic drag. Some flow control method provides the possibility to modify the flow separation to reduce the development of the swirling structures around the vehicle. In this study, a family van is modeled with a modified form of Ahmed's body by changing the orientation of the flow from its original form (modified/reversed Ahmed body). This model is equipped with a suction on the rear side to comprehensively examine the pressure field modifications that occur. The investigation combines computational and experimental work. Computational approach used a commercial software with standard kepsilon flow turbulence model, and the objectives was to determine the characteristics of the flow field and aerodynamic drag reduction that occurred in the test model. Experimental approach used load cell in order to validate the aerodynamic drag reduction obtained by computational approach. The results show that the application of a suction in the rear part of the van model give the effect of reducing the wake and the vortex formation. Futhermore, aerodynamic drag reduction close to 13.86% for the computational approach and 16.32% for the experimental have been obtained.
Supervising Success: Strategies for Supporting Fast-track Postgraduate Students in Indonesia Hari Setyowibowo; Nur Izzah, Nisrina; Juniarti Duwi Lestari; Asep Khoerudin; Harinaldi; Nuri Andar Wulan
Humanitas: Indonesian Psychological Journal Volume 21 (2) 2024
Publisher : HUMANITAS published by Universitas Ahmad Dahlan.

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26555/humanitas.v21i2.929

Abstract

Students in fast-track postgraduate programmes face unique challenges, including intense academic pressure, role management difficulties, and high expectations for research output. This study, using the Self-Determination Theory (SDT) framework, specifically investigated good practices of supervisory strategies to improve postgraduate student well-being and academic performance in such accelerated programs. We collected data through online Focus Group Discussions (FGDs) with 264 supervisors from various academic fields and then analysed the data using thematic analysis. We incorporated expert review, FGDs facilitator guidance, and rigorous data validation processes to ensure trustworthiness. The findings reveal several critical challenges students face, including academic, self-management, relationship, financial, and program-related difficulties, highlighting areas where enhanced supervisory support is crucial. Furthermore, we found that supervisors assist students by providing essential academic information, offering structured guidance, and fostering a supportive environment. These findings can guide improved supervision strategies in a postgraduate fast-track programme.
Flame Stability And Fuel Efficiency Of Gas Diffusion Flame On The Backward Facing Step Harinaldi Harinaldi; Maymuchar Maymuchar
Scientific Contributions Oil and Gas Vol 32 No 1 (2009)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.32.1.835

Abstract

Propane and butane injection into the recirculation zone in the fuel area with backward-facing step has a significant effect to the diffusion flame with the characteristic stability which depends on the velocity of the free air stream, the injection position from the step and the injection position to step height ratio. The test result shows that there are two main stable diffusion flames: a stabilized flame in the recirculation zone and a stabilized flame in the shear layer region. There is a decrease of the fuel efficiency due to the effect of the greater ratio of the injection position to the step height and the farther injection position from the steps. The effect of the free air stream velocity is much more significant the injection location near the steps.
Liftoff of Propane - Air Diffusion Flames By Axis Symmetric Co-flow Air Injection I Made K Dhiputra; Harinaldi Harinaldi; NK Caturwati; Dimitri Rulianto
Scientific Contributions Oil and Gas Vol 32 No 3 (2009)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.32.3.853

Abstract

Combustion of gas with diffusion system is widely used in many residential gas appliances like stove, engine furnaces and industrial furnaces. Phenomenon of lifted flame is often happened at diffusion flame where the stream of fuel and air into combustor flow separately. Hence the combustion process needs time so that mixing of air and fuel reach the condition ready for burnt. This condition make the burner tip protected from high thermal load and more safe to operate. In this paper, propane was ejected into quiescence air through nozzle having 1.8 mm holes diameter. Fuel flow rate was increased until liftoff conditions exceed; hereinafter flow rate of fuel was made constant at 69 ml/s and air was ejected around of fuel with axis symmetric flow. Liftoff behavior of diffusion flames was investigated for various air flow rate: 17.9 ml/s – 89.9 ml/s. Lifted distance decreased from 130 mm to 90 mm when air was injected with flow rate of 19.1 ml/s, however, it increased to 100 mm when air flow rate increased to 35.9 ml/s. Cold-flow simulation showed the moderate air flow rate give a faster density degradation at axial line compared to larger air flow rate. It means moderate flow rate of air support a better air-fuel mixing than faster one.
Effect of Graphene Oxide Addition on Spark Ignition Engine Performance and Cycle-to-cycle Variation with Gasoline-ethanol Fuel Askar Adika Agama; Ahmad Syihan Auzani; Alfian Ferdiansyah Madsuha; Hendra Hermawan; Ade Kurniawan; Mokhtar Mokhtar; Aswin Aswin; Nasruddin Nasruddin; Yulianto Sulistyo Nugroho; Harinaldi Harinaldi
Automotive Experiences Vol. 9 No. 1 (2026)
Publisher : Universitas Muhammadiyah Magelang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31603/ae.14237

Abstract

A fuel blend of gasoline and ethanol increases octane, meets air quality standards, and satisfies renewable fuel mandates, but the blend does not always result in perfect bonding, causing fuel separation and increasing cyclic variation. To overcome these limitations, up to 60 ppm graphene oxide (GO) nanoparticles were added into an 80:20 gasoline-ethanol blend (E20) and tested for the first time on a spark-ignition (SI) engine. The engine performance was evaluated by measuring cyclic variation, combustion stability and pressure, torque and power, specific fuel consumption, and CO2 emission. The acquired data were then statistically treated by using a coefficient of variation (COV) and then evaluated with Response Surface Methodology (RSM) in order to demonstrate a strong ability to accurately predict the optimization. Results show that the addition of GO nanoparticles into the E20 reduced the COV by up to 19.54% at an engine speed of 8000 rpm when compared to E20 alone, while the torque and power both increased by 5% at 5500 rpm. The specific fuel consumption of the GO-E20 blend was up to 15% higher than that of E20, with a decrease in CO emission but an increase in CO2 emission. Generally, the E20GO blend positively impacts the SI engine’s cyclic stability and performance, but its potential adverse effects on the environment and health must be carefully considered.
Aerodynamic effect of windbreak on the crosswind phenomenon on a high-speed train Harinaldi Harinaldi; Naufal P Ramadhan
Prosiding SNTTM Vol 23 No 1 (2025): SNTTM XXIII October 2025
Publisher : BKS-TM Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.71452/xk93bt57

Abstract

Crosswind greatly affects the aerodynamic performance and operational safety of the high-speed train. Windbreak is one of the windproof facilities commonly used for high-speed trains in windy areas. This study aims to see how variations in windbreak height (3.8 m; 4.4 m; and 5.2 m) can affect the aerodynamic performance of high-speed trains. 3 aerodynamic coefficients (drag, lift, and rolling moment) of the HST were compared when the train passed the track under the same conditions using the ANSYS FLUENT CFD simulation. Sudden changes in aerodynamic loads can be seen from the visualization of the pressure contour. First, the aerodynamic coefficient of the train will decrease significantly when the train begins to enter the windbreak. Second, the ‘IN’ process of the windbreak track has a larger aerodynamic load fluctuation than the ‘OUT’ process. Third, the height of the windbreak does not significantly change the trend of the aerodynamic coefficient graph, there is only a phase difference and the magnitude of the amplitude formed. The highest average drag and lift coefficient occurs at a height of 5.2 m, which is 0.29 and 0.011. Meanwhile, the highest average rolling moment coefficient occurs at a windbreak height of 3.8 m, which is 0.0028
Spatial Analysis of Fish Diversity, Evenness, and Dominance During the Seasonal Transition Period for Ecosystem Health Assessment Ainy, Noer Sarifah; Sjahfirdi, Luthfiralda; Patria, Mufti Petala; Harinaldi, Harinaldi; Mujadid, Iqbal
Journal Of Biology Education Research (JBER) Vol. 7 No. 1 (2026): JBER (Journal Of Biology Education Research), Vol.7 No.1 (2026)
Publisher : Program Studi Pendidikan Biologi FKIP Universitas Pakuan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.55215/jber.v7i1.105

Abstract

Freshwater ecosystems, particularly small lakes, play a crucial role in maintaining biodiversity and supporting essential ecological functions, yet they are highly vulnerable to environmental disturbances. Small lakes are increasingly exposed to anthropogenic pressures such as land use change, nutrient enrichment, and declining water quality, making biological assessment essential for detecting ecosystem degradation. This study aimed to identify segment level patterns of fish diversity, evenness, and dominance during the seasonal transition period and to determine whether these patterns can distinguish relatively balanced ecological zones from priority stress zones for ecosystem management. An ecologically based quantitative descriptive approach was applied using spatial zoning of inlet, middle, and outlet segments. Fish assemblages were assessed using the Shannon–Wiener diversity index (H′), Evenness (E), and Simpson’s dominance index (D). The results revealed clear spatial variation in community structure among sampling segments. Some systems exhibited strong internal ecological gradients characterized by decreasing diversity and increasing dominance toward downstream segments, whereas others showed more transitional or relatively uniform patterns. Community composition analysis indicated assemblage compression and potential biotic homogenization driven by a limited number of dominant taxa. Exploratory analyses further suggested that higher alkalinity, hardness, and chlorine levels were associated with lower diversity and greater dominance. These findings demonstrate that fish community indices provide effective biological indicators of ecosystem condition and can support spatially targeted monitoring, conservation, and management of small freshwater ecosystems. The study also highlights the importance of incorporating spatially explicit community assessments into ecosystem health evaluation frameworks.
Co-Authors Ade Kurniawan Ainy, Noer Sarifah Asep Khoerudin Askar Adika Agama Aswin Aswin Auzani, Ahmad Syihan Budiarso Budiarso Budiarso Budiarso, Budiarso Caturwati, NK Christoforus Deberland Damora Rhakasywi Dhiputra, I Made K Dimitri Rulianto Engkos A. Kosasih, Engkos A. Engkos Achmad Kosasih Engkos Kosasih Engkos Kosasih Hari Setyowibowo Hendra Hermawan I Gusti Made Teryanto I Gusti Made Teryanto, I Gusti Made I Made K Dhiputra James Julian Juniarti Duwi Lestari Lay Teryanto, I Gusti Made Fredy LUTHFIRALDA SJAHFIRDI Madsuha, Alfian Ferdiansyah Maymuchar Maymuchar Maymuchar, Maymuchar Mokhtar Mokhtar Mufti Petala Patria Mujadid, Iqbal Nasruddin Naufal P Ramadhan NK Caturwati Nur Izzah, Nisrina Nuri Andar Wulan Parker Stefan, Parker Revan Difitro, Revan Rulianto, Dimitri Rustan Tarakka Rustan Tarakka Sabar Pangihutan Simanungkalit Sabar Simanungkalit Sabar Simanungkalit, Sabar Trisno Sri Suparyati Soenarto dan Dibyo Pramono Agung Wibowo Warjito Warjito Warjito Warjito, Warjito Yulianto Sulistyo Nugroho