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The purpose of this research was to ascertain whether there had been any improvement in students' metacognitive and critical thinking skills through the development of the 'Teaching Factory Based on Troubleshooting' (TEFA-T) model in automotive vocational learning. The research had both quantitative and qualitative components and applied the 4D procedures, viz define, design, develop and disseminate. The subjects for the control and experimental groups were 32 students, and each was each group used an effectiveness test. The results showed that the TEFA-T learning model carried out the novelty value of the model syntax using the following activity steps: (1) identifying product problems, (2) defining the product problems, (3) generating and selecting several alternative solutions, (4) designing solving techniques, (5) ordering work contracts, (6) designing a product work schedule, (7) executing orders, (8) quality control, and (9) assessment. The test results showed that the TEFA-T Learning Model is valid using the Aiken'V formula and Confirmatory Factor Analysis (CFA) and Structure Equation Modeling (SEM), with a Chi-Square and x2 /df values of 219.76 and 0.8292, used to determine the model fit test (goodness-of-fit models). Furthermore, the practicality test declared it "Very Practical" with an average score of 4.56 and an Achievement of 90.02%. In conclusion, using the TEFA-T learning model to improve students' academic achievement, metacognitive, and critical thinking skills appeared to be effective (Sig. 2- tailed value is less than 0.05).

Cellulose-based film has gained popularity as an alternative to synthetic polymers due to its outstanding properties. Among all types of cellulose materials available, cellulose nanofiber (CNF) has great potential to be utilized in a diverse range of applications, including as a film material. In this study, CNF biocomposite film was prepared by using polyvinyl alcohol (PVA) as a matrix and Uncaria gambir extract as a filler. This study aims to investigate the effect of Uncaria gambir extract on the optical properties and thermal stability of the produced film. The formation of the CNF biocomposite films was confirmed using Fourier Transform Infrared Spectroscopy, their transmittance characteristics were measured using UV-Vis spectroscopy and a transmittance meter, while their reflectance was determined using a reflectance meter. The results revealed that the addition of Uncaria gambir extract to the CNF biocomposite film improved its UV-shielding properties, as indicated by the lower percentage of transmittance in the visible region, 10%–70%. In addition, its reflectance increased to 10.6% compared to the CNF film without the addition of Uncaria gambir extract. Furthermore, the thermal stability of the CNF biocomposite film with the addition of Uncaria gambir extract improved to around 400°C–500°C. In conclusion, the results showed that CNF biocomposite film prepared by adding Uncaria gambir extract can be a promising candidate for optical and thermal management materials. [ABSTRACT FROM AUTHOR]

The ducting system is made up of 90° elbows and a few other fittings and accessories in addition to straight ducts. The friction loss, separation loss, and secondary flow loss are the main causes of the pressure decrease in an elbow, and they all increase with the presence of elbows. Utilizing too much energy to propel the flow is a cost associated with pressure loss. The aim of this research is to investigate turbulent flow via 90° square elbows and a square-sectioned duct through experimental methods by adding a circular turbulator (CT) close to the elbow wall's inner radius. The Reynolds numbers (ReDh) used in this research are 1.6x104, 4.8x104, and 9.5x104, with average flow velocities of 2 m/s, 6 m/s, and 12 m/s. Circular turbulators are added to the inner walls with angular positions (α) of 5°, 10°, 15°, and 20°. The results showed that the turbulence intensity increased toward the inner radius wall of the elbow in ducting with CT. For this study, the flow within the ducting with the CT is generally more turbulent than the flow inside the ducting without the CT. By including CT, it was possible to reduce the overall pressure loss in ducting with an elbow. The pressure reduction at two ReDh values (1.6x104 and 4.8x104) was only lessened by CT positioned at α = 10°, 15°, and 20° out of the four CT placements. Conversely, CT positioned at α = 5° can only effectively mitigate pressure decrease at ReDh = 1.6x104. CT installation cannot lessen the pressure drop that happens in the ducting at a value of ReDh = 9.5x104. CT placement at the three α values often helps to lower the pressure drop in the ducting. Using the CT, positioned at α = 15°, is the greatest strategy to reduce the overall pressure decrease. [ABSTRACT FROM AUTHOR]

The extent of existing corn land in Indonesia and the activities carried out by farmers in corn farming requires the innovation of an effective and efficient corn harvesting machine. This underlies the Research Center for Appropriate Technology located at the Faculty of Engineering, Universitas Negeri Padang to design a corn harvesting tractor that can facilitate the community in carrying out activities in the agricultural sector. The design of the corn harvester tractor consists of the harvester mechanism, the frame, the engine, and the powertrain. The frame is a crucial component of the corn harvester tractor, and its strength depends on its shape and proportions. The construction’s strength of the frame must take into account both safety considerations and the structure’s strength. The purpose of this study is to evaluate the frame strength of a corn harvester tractor made of steel of the ASTM A36 type. In this study, the von Mises stress that exists in the frame is used to calculate the strength of the frame of a corn harvester tractor. In numerical analysis, the chassis utilizes two tests with various load variations, namely the concentrated load and the load that is evenly distributed on the surface. The simulation results show that the frame of the corn harvester tractor can withstand the load well. The results of the stress analysis that occurs on the frame of the corn harvester tractor are that the maximum stress that occurs due to the concentrated load on the frame is 3.248 MPa. While the maximum stress that occurs due to the distributed load acting on the frame is 3.510 MPa. In addition, information was obtained that the value of the safety factor for the frame with ASTM A36 type met the component requirements that could withstand concentrated loads and distributed loads. [ABSTRACT FROM AUTHOR]

The humidity used in the painting process greatly determines the result of painting the car body. This study aims to develop a dry air compressor that can be used to overcome car paint defects. This system consists of a 2 HP compressor engine for sucking air from the atmosphere, two air collection tubes where the first tube contains air obtained from the atmosphere and the second tube contains dry air obtained from the first tube. The inside of the first tube is given a copper coil measuring 5 mm in diameter which is connected to a 120-watt cooler while the second tube is not given a copper coil. Each tube has a diameter of 50 cm and a height of 100 cm. The addition of copper coil aims to separate air from water by means of the condensation process which is the development of this study. Testing of compressor performance is done by turning on the compressor with the exhaust valve closed. After 60 minutes, the air pressure in each tube increased from 0 Psi to 89 Psi, the humidity decreased from 52 % to 38 %, and the temperature decreased from 31.6 °C to 18.2 °C. To see the effect of cooling on the air, the exhaust valves on both tubes were opened. In the first tube there is water coming out, as much as approximately 100 ml while in the second tube there is no water coming out. The water that comes out of the first tube is caused by the condensation process that separates the air from the water and due to the influence of gravity the water falls to the bottom of the tube. The dry air contained at the top of the first tube is flowed into the second tube and is ready to be used for painting the car body. The painting results show that there are no more small holes or paint defects on the paint surface. [ABSTRACT FROM AUTHOR]