MOTIVECTION : Journal of Mechanical, Electrical and Industrial Engineering

The Effect of Activated Carbon From Palm Oil Kernel Shells on Waste Cooking Oil for Soap Production

Wed, 18 Feb 2026 00:00:00 +0000

This study addresses the existing limitation in integrated waste valorization approaches by combining palm kernel shell–derived activated carbon production, waste cooking oil purification, and solid soap manufacturing within a UMKM-based circular economy model. Unlike previous studies that focus separately on adsorbent synthesis or oil purification, this research evaluates the adsorption performance quantitatively and links it directly to downstream soap quality. Activated carbon was synthesized via controlled pyrolysis (400 °C) followed by KOH activation (800 °C) and characterized using FTIR. The purification process reduced free fatty acid (FFA) content from 2.35 ± 0.02% to 0.43 ± 0.01%, corresponding to an adsorption efficiency of 81.7%. The adsorption capacity was calculated and statistical validation was performed in triplicate experiments. The resulting solid soap exhibited stable pH (8.89 ± 0.05) and satisfactory physical properties. These findings demonstrate the scientific and practical contribution of palm kernel shell activated carbon as a sustainable bioadsorbent supporting circular economy implementation at the UMKM scale.

Determination of Optimal Route for Distribution of Rice Food Assistance in City X using the Cuckoo Search Algorithm

Eri Wirdianto, Muhamad Gustaffo Bintang, Farhan Azhari — Mon, 02 Mar 2026 03:25:57 +0000

As distribution requirements become more complex, various VRP variants have been developed to address specific challenges. Among them, the Vehicle Routing Problem with Time Windows (VRPTW) adds the constraint that each customer must be served within a predefined time frame, making the routing process considerably more difficult. In this study, we propose a new approach that uses the Cuckoo Search (CS), a metaheuristic algorithm based on Lévy flights. This combination of Lévy flights and CS is designed to maximize exploration of optimal solutions while allowing dynamic route variations. This study aims to evaluate the effectiveness of this approach in optimizing rice food assistance distribution routes in City X. The exact method yielded a global optimum solution consisting of four routes with a minimum total distance of 222 km, requiring 2 hours 36 minutes 27 seconds of computation. In comparison, the cuckoo search algorithm also produced four routes, with a slightly longer total distance of 244 km but a significantly shorter computation time of 1 minute 39 seconds. This represents a difference of about 22 km (9.91%) from the exact solution, demonstrating that for VRPTW, the cuckoo search algorithm can generate near-optimal results with minimal deviation and substantially reduced computational effort.

Evaluation of the Stability of the Anaerobic Digestion Process of POME Based on the Correlation of VFA, Alkalinity and Methane Content

Thu, 05 Mar 2026 00:00:00 +0000

Palm Oil Mill Effluent (POME) contains a high organic load and requires effective treatment to prevent environmental pollution while enabling energy recovery. Anaerobic digestion is widely applied for POME treatment due to its ability to reduce organic pollutants and produce methane-rich biogas; however, its performance is highly dependent on process stability. This study aims to evaluate the stability of the anaerobic digestion process of POME through correlation analysis among volatile fatty acids (VFA), total alkalinity (TA), suspended solids (SS), and methane content (CH₄) using field operational data. The study was conducted at an industrial-scale biogas plant treating POME, where slurry samples were collected periodically from multiple biodigester units representing different digestion stages. VFA and TA were analyzed using acid–base titration, SS by gravimetric method, and methane content using a gas analyzer. The results show that the anaerobic digestion process operated under stable mesophilic conditions (35 ± 2 °C) with reactor pH maintained in the optimal range of 6.8–7.5. VFA concentrations remained relatively low (approximately 480–510 mg/L), supported by sufficient alkalinity (about 5,600 mg/L as CaCO₃), resulting in a low VFA/TA ratio (~0.09), indicating stable process conditions. A significant reduction in COD from approximately 41,700 ppm in the influent to about 7,200 ppm in the effluent was achieved, corresponding to a COD removal efficiency of 83%. Methane content in the biogas remained stable at ≥55%, supporting effective energy utilization without flaring. These results demonstrate that maintaining a balanced relationship among VFA, alkalinity, suspended solids, and operating conditions is essential for ensuring stable anaerobic digestion and consistent biogas quality in industrial-scale POME treatment systems.

Stress Distribution and Rib Reinforcement Design in Konstruksi Sarang Laba-Laba (KSLL) Foundations Using the Winkler Method

Akbar Kurnia, Andriani Andriani, Abdul Hakam — Thu, 23 Apr 2026 03:37:45 +0000

Previous studies on Konstruksi Sarang Laba-Laba (KSLL) foundations have primarily focused on bearing capacity and overall foundation performance, while limited attention has been given to soil–structure interaction, stress distribution, and reinforcement design of KSLL ribs using the Winkler method. This study investigates the stress distribution in KSLL foundation ribs and determines the corresponding reinforcement requirements under different subgrade conditions. A numerical modeling approach was employed using a structural analysis program to simulate KSLL foundations on three soil categories—soft, medium, and stiff soils—with three rib/column connector dimensions of 30 × 30 cm, 50 × 50 cm, and 80 × 80 cm. The analysis was based on the modulus of subgrade reaction (Ks) to represent Winkler-type foundation springs. The results show that Ks increases with soil stiffness, indicating stronger subgrade support in stiffer soils. Soft soil consistently produced the highest normal stress, shear stress, and settlement, followed by medium and stiff soils. The ratio of normal stress between soft and stiff soils ranged from 1.5 to 3.0, while the shear stress ratio ranged from 1.4 to 2.0 at support zones and 1.6 to 1.9 at span regions. The effect of column-size variation on normal stress was relatively limited, although larger column dimensions reduced shear stress at supports by improving force distribution. The required main reinforcement increased with normal stress, reaching 7–8 bars in soft soil, 6 bars in medium soil, and 5–6 bars in stiff soil. Shear reinforcement spacing decreased as shear demand increased, with minimum spacing of 110 mm in soft soil, 150 mm in medium soil, and 260 mm in stiff soil. These findings demonstrate the importance of incorporating soil–structure interaction, subgrade stiffness, and rib-specific reinforcement design in KSLL foundation analysis to achieve safer and more efficient shallow foundation design.

Mining Sequence Compliance and Production Performance in an Open-Pit Coal Mine: A Case Study of Pit Rista, South Sumatra

Ambun Qodri, Fariz Aditya, Fadhilah Fadhilah, Tri Gamela Saldy — Thu, 23 Apr 2026 03:47:20 +0000

This study assesses coal and overburden production efficacy for the mining sequence at Pit Rista, PT Dewa Sukses Mandiri, South Sumatra, during July and August 2025, and recommends operational enhancements to facilitate production objectives in the following months. The investigation was prompted by the inability to meet monthly production targets, as evidenced by insufficient effective working hours, excessive downtime, low equipment availability, and discrepancies between planned and actual mining progress. A quantitative evaluative method was employed utilizing primary data consisting of loading and hauling cycle durations, alongside secondary data such as production reports, working hours, downtime records, mine design, and mining sequence plans. The examination encompassed equipment productivity, job efficiency, match factor, physical availability (PA), use of availability (UA), Pareto analysis of downtime, and a comparison between planned and actual implementation of the mining sequence. The findings indicate that production deficits in July and August 2025 were mostly attributable to diminished effective working hours resulting from operational and mechanical delays, low PA and UA values, and discrepancies between the planned mining sequence and actual field execution. In July, the primary cause of lost time was the lack of hauling help, however in August, weather-related delays emerged as the principal limitation. These conditions impeded mining advancement and diminished overall output efficacy. In light of these findings, production optimization should prioritize enhancing mining sequence execution, reinforcing equipment maintenance and oversight, reconfiguring pit front and haul road geometry, and regulating haul road gradients to minimize downtime and enhance operational efficiency.

Mode-Dependent Effects of a Piggyback Throttle Controller on Torque and Power in a 1500 cc EFI Engine

Thu, 23 Apr 2026 03:49:59 +0000

The rising adoption of aftermarket devices in the car modification industry has heightened interest in the piggyback throttle controller as an effective means of modifying throttle response without substituting the original ECU. Nonetheless, its impact on torque and power remains inadequately substantiated through controlled experimentation. This study experimentally assessed the impact of a 9-Drive piggyback throttle controller on the performance parameters of a 2011 Toyota Yaris 1500 cc EFI engine utilizing a chassis dynamometer. The car underwent testing under four conditions: no treatment, Standard mode, F1 mode, and ECO mode, with each condition replicated three times. The findings indicated that F1 mode generated the maximum average torque, attaining 177.13 Nm, which was 15.03 Nm greater than the untreated condition. Conversely, ECO mode yielded the highest average power at 98.60 HP, whereas Standard mode exhibited just negligible variations in both metrics. The data demonstrate that the controller did not produce a consistent performance enhancement across all modes, but instead altered the engine's output characteristics in a mode-dependent fashion. Under the current testing conditions, F1 mode exhibited a more pronounced torque-oriented response, while ECO mode demonstrated marginally greater power output. The findings indicate that a piggyback throttle controller can alter engine response characteristics, however its impact must be assessed in relation to the chosen mode and the particular performance metric under evaluation.