Semesta Teknika

Analysis of Machine Effectiveness to Minimize Six Big Losses in the Palm Oil Industry

2025-02-03T14:46:44+07:00

PT XYZ is oil industry that processes CPO from oil palm, with a daily production target of 1,000 tons and a flow rate of 41.67 tons per hour. However, in 2019, the actual flow rate fell short of expectations. This study aims to improve equipment effectiveness in the refinery division through enhanced machine maintenance. Using the OEE method, the study identifies machines with the lowest effectiveness for priority improvement. Analysis of these machines, integrating OEE, FMEA, and TPM, reveals that the Niagara filter machine has the lowest effectiveness. The OEE value is 82.14%, primarily due to breakdown losses and idling minor & stoppage losses. Based on the highest RPN values, three improvement proposals are suggested. Such as routine field checking on every shift, scheduling system for maintenance processes, and training operators about how to always ensure and control the pressure when operating the machine. So, this improvement expected to raise the OEE more to 84.16%.

Seismic Performance of Multi-Story Reinforced Concrete Frame Structures Due to Vertical and Horizontal Irregularities

2024-12-21T09:41:17+07:00

The irregularities in structures affect their seismic performance, particularly in earthquake-prone areas, such as Indonesia. This study evaluates the seismic performance of multi-story reinforced concrete frame structures with vertical and horizontal irregularities. The building has 12 floors and features two different plans and vertical irregularities, namely the L and H buildings. Each horizontal irregularity has five variations of vertical irregularity. Th-e frame structure is analyzed using STERA 3D software for non-linear dynamic time-history analysis. El-Centro, Kobe, and Parkfield earthquake time history data were used in this study. The seismic behavior investigated in this study consisted of base shear force, lateral deformation, stiffness, displacement, drift ratio, maximum acceleration, and capacity curve. Numerical simulation results indicate that each model performs differently when subjected to the same seismic load and material properties. It can be concluded that vertical irregularity significantly affects the seismic performance of high-rise reinforced concrete structures. The maximum shear force with vertical irregularity is 133% higher for the L-Shape and 169% higher for the H-Shape compared to a building without vertical irregularities.

The Comparation of Building Information Modelling and Conventional Method in Planning Multi-storey Building Structure

2024-11-29T10:22:25+07:00

The construction sector in Indonesia is experiencing rapid development so that Architectural, Engineering Construction (AEC) companies compete with each other and adopt technology that significantly increases the efficiency and effectiveness of construction project implementation. This study is aimed to compare the implementation of BIM with conventional method based on the duration of process, the number of personnel needed and the budget of implementation. Research data are data and information obtained through questionnaires and interviews with 3 (three) AEC companies in Padang city, either implementing BIM or conventional method. Based on the result, it was concluded that conventional method requires longer time in planning structural work compared to BIM method with reducing time 76.4% in the design process, 33.3% in the number of personnel and 16.11% in salary costs compared with BIM method. By efficiency and sustainable benefits considered, it is necessary to encourage AEC companies in Padang city to implement BIM method in their business processes.

Photovoltaic-Thermal Systems for Producing Hot Water: A Thermal Study

2025-03-27T14:29:26+07:00

Photovoltaic technology harnesses solar energy to generate electrical power. With high solar radiation intensity, battery overcharging is risky due to its limited capacity. The surplus electricity generated by solar modules can be converted into thermal energy. This study analyses the thermal behavior of water heating processes within a storage tank in the photovoltaic system. The experiment included a solar module, controller, battery, storage tank, water pump, heating element, and five thermocouples. The study was conducted outdoors over three days, and solar radiation intensity and water temperature were recorded in the tank. The collected data was used to evaluate the photovoltaic-thermal system, especially in the thermal aspect. Results showed that higher solar radiation intensity led to increased water temperatures. The study's highest recorded cumulative thermal energy and efficiency were 1502.74 kJ and 29.34%, respectively. The photovoltaic systems can serve as sources of both electrical and thermal energy.

Evaluating Flow Resistance in Straight Channels Using 2-Point Velocity Measurements

2025-02-13T09:24:03+07:00

Accurately measuring Manning’s roughness coefficient is crucial for enhancing the precision of hydraulic models and supporting informed decision-making in water resource management. Traditionally, this coefficient is determined using the cross-sectional mean velocity, which may introduce inaccuracies due to its approximate nature. However, estimating Manning’s roughness coefficient through flow velocity distribution analysis remains a relatively underexplored approach. This study aims to improve the accuracy of estimating Manning’s roughness coefficient by analyzing the velocity distribution at two vertical positions within the flow: z/H = 0.2 and z/H = 0.8. Secondary velocity data were obtained from four locations to support this investigation: a laboratory flume, the Selokan Mataram irrigation channel, the Kuning River, and the Opak River. The research methodology involves simplifying and applying analytical equations needed to determine Manning’s roughness coefficient based on the velocity profile. The results indicate that, in natural river systems, Manning’s roughness coefficient ranges from 0.035 to 0.095 at z/H = 0.8 and z/H = 0.2 and from 0.032 to 0.085 at z/H = 0.4 and z/H = 0.2.

Photovoltaic Efficiency and Technology Innovation in Renewable Energy: A Systematic Literature Review

2025-02-04T10:45:58+07:00

Solar photovoltaic (PV) technology plays a critical role in advancing renewable energy by converting sunlight into electricity. However, its effectiveness relies heavily on continuous innovation to enhance efficiency. Indonesia’s transition towards renewable energy is driven by significant solar potential, yet challenges persist in adopting optimal PV technologies under tropical conditions. This study conducts a Systematic Literature Review (SLR) of 41 journal articles published between 2020 and 2024, using the PRISMA method and focusing on the most-cited works. Results show that inorganic PV technologies remain dominant due to high efficiency (up to 38.9%), while organic PV offers flexibility and cost advantages despite lower efficiency (1.5%–31%). Key innovations include hybrid systems and advanced materials such as quinoxaline-based structures. The study identifies the most viable PV technologies for tropical regions and highlights the growing trend in global research. These findings provide valuable insights for policymakers and researchers in developing sustainable solar energy strategies.