Camshaft lift is an important parameter that determines the height of the valve lift, calculated from the valve position when it is completely closed to the fully open position. This component plays a crucial role in regulating the flow of the air and fuel mixture into the combustion chamber. This study aims to improve the performance of a 200cc 4-stroke motorcycle engine through camshaft lift modification, which is expected to affect the characteristics of engine torque and power. Modifications were carried out by designing two types of modified camshafts, namely series A and series B, as a comparison to the standard camshaft. The research method used is experimental testing using a dynamometer to measure engine torque and power at various speeds, ranging from 4,000 to 10,000 RPM. The data obtained were analyzed to determine the effect of each type of camshaft on engine performance. The test results show that the B series camshaft provides the most significant performance improvement compared to the standard and A series camshafts. At 7,500 RPM, the standard camshaft produces an average torque of 19.2 Nm, the A series camshaft 19.6 Nm, while the B series camshaft reaches 21.2 Nm. Meanwhile, at 10,000 RPM, the average power of the standard camshaft is recorded at 22.2 HP, the A series camshaft 24.1 HP, and the B series camshaft reaches 26.3 HP. This increase indicates that the camshaft lift modification is able to optimize the duration and height of the valve opening, so that the supply of the fuel and air mixture to the combustion chamber becomes more efficient. Thus, camshaft modification, especially the B series, is an effective and applicable solution in increasing the performance output of a 200cc motorcycle engine without having to make major changes to the overall engine structure.

Motorcycle engine performance is highly dependent on the air intake system, which plays a crucial role in the combustion process. One common method for improving engine performance is modifying the intake system, either by installing additional devices or adjusting the quantity of incoming air. One innovation that is starting to be widely used is the Jet Ranger, an additional device on the intake duct that is claimed to be able to increase air flow into the combustion chamber. This study aims to determine the effect of the use of Jet Ranger and variations in the quantity of incoming air on the maximum power of a 150 cc motorcycle engine, as well as to analyze the interaction between the two variables. The study was conducted using an experimental method with a two-way factorial approach. The independent variables in this study consisted of two factors, namely the use of Jet Ranger (without Jet Ranger and with Jet Ranger) and variations in the quantity of incoming air divided into four levels (0.008; 0.012; 0.016; and 0.020 kg/s). Maximum power testing was conducted using a Leads dynotest, while the mass of incoming air was calculated based on air velocity measured using a digital anemometer. The test data were statistically analyzed using a two-way ANOVA to identify the effect of each factor and the interaction between them on engine power. The results of the study indicate that the use of Jet Ranger significantly increases engine power. Variations in the quantity of intake air also significantly affect the power generated. In addition, the interaction between the use of Jet Ranger and the quantity of intake air is proven to have a significant impact on increasing the maximum engine power. These results are in line with the theory of intake systems which states that increasing optimal air flow can increase the volumetric efficiency of the engine, and are supported by findings from previous studies. Therefore, these findings can be used as a reference in the development of air intake systems on motorcycles to achieve more optimal engine performance.

Rapid technological developments have penetrated various aspects of human life, including data and information security. Amidst the threat of data leaks and misuse, information protection has become crucial. One solution to maintain data confidentiality is to implement cryptography technology. Cryptography is the study of techniques to secure messages so they cannot be read by unauthorized parties. This process is carried out by encoding the original message (plain text) into an unreadable form (cipher text), which can only be understood by those who possess the key to decrypt it. This study used the Caesar Cipher algorithm, a form of classical cryptography. This algorithm uses a substitution method, where each letter in the message is shifted by a certain amount based on a predetermined key. Caesar Cipher is a symmetric algorithm, meaning the key used for encryption is also used for decryption. The security of this algorithm lies in the secrecy of the key, which is known only to the sender and recipient of the message. This method is relatively simple, but still relevant for securing data with low to medium sensitivity levels. This study used WhatsApp messages as the object to be encrypted using the Caesar Cipher algorithm. The results show that encrypted messages become unintelligible without prior decryption. This demonstrates that the Caesar Cipher can protect messages from unauthorized parties. Therefore, implementing this algorithm can be an initial solution for maintaining data confidentiality in digital communications, especially on platforms vulnerable to eavesdropping or unauthorized access. Its primary benefit is maintaining message integrity and confidentiality to prevent misuse.
 

This research investigates the underlying factors that shape the interest of students from the 2024 cohort in enrolling in the Bachelor of Mechanical Engineering Education Program at the Faculty of Engineering, Universitas Negeri Padang. Utilizing a descriptive quantitative methodology, data were gathered through a structured, closed-ended questionnaire administered to the entire cohort, which consisted of 89 students. The analysis reveals that the overall level of student interest is categorized as high, with a notable percentage of 55%. Several key variables were identified as influential: (1) self-awareness factors encompassing physical capabilities, intellectual aptitude, intrinsic motivation, and innate talent were rated in the very high category at 56%; (2) familial influences such as the provision of information, emotional support, and parenting styles also ranked very high at 46%; (3) school-related elements including the accessibility of school information systems, teacher roles, peer dynamics, and hands on learning experiences were classified in the high category with 44%; and (4) social media engagement specifically the frequency of use and the quality of educational content was likewise in the high category, scoring 48%. These findings underscore the multifaceted nature of student decision-making, with self-awareness emerging as the most prominent determinant in shaping academic program choices. The study highlights the need for educational institutions to consider these interrelated dimensions when developing recruitment strategies and academic guidance frameworks.

This study uses a qualitative method to examine the influence of sustainable manufacturing systems on the competitiveness of industrial companies in Indonesia. In an increasingly competitive global market, implementing sustainability principles in manufacturing systems has become a vital strategy to enhance operational efficiency, reduce environmental impact, and strengthen a company’s image in the eyes of consumers and stakeholders. This research focuses on how industrial companies in Indonesia integrate economic, social, and environmental aspects into their production processes and how such integration contributes to long-term competitiveness. Data were collected through in-depth interviews with production managers, analysis of internal company documents, and direct observation of sustainable manufacturing practices. The findings reveal that companies consistently applying sustainable manufacturing systems are able to improve product quality, expand market share, and enhance customer loyalty. Additionally, they are more adaptive to environmental regulations and market trends demanding corporate social responsibility. Thus, sustainability becomes a strategic factor in enhancing industrial competitiveness in Indonesia.

Internal combustion engines generate thermal energy through the combustion of an air-fuel mixture. The incoming air must be filtered, as it contains impurities and particles. While air filters are commonly made from paper, they can also be developed using organic waste materials such as sugarcane bagasse and rice husk. This study aims to analyze the effect of biocomposite air filters on engine power, torque, and specific fuel consumption (SFC), by varying the material composition and the number of pleats, and comparing the results with those of a standard air filter. The method used is a quantitative experimental approach involving dyno testing on a 150 cc motorcycle engine. The tested material compositions include 50:50, 40:60, 30:70, 60:40, and 70:30 (sugarcane bagasse\:rice husk), with pleat counts of 28, 26, and 24. Results showed that the biocomposite filter with 28 pleats and a 30:70 composition delivered the best performance, producing 18.47 Hp and 16.66 Nm of torque—higher than the standard filter’s 17.98 Hp and 15.52 Nm. In terms of fuel efficiency, the 26-pleat filter with a 50:50 composition recorded the lowest SFC at 41.90 g/kWh, significantly better than the standard filter’s 53.03 g/kWh. Conversely, the 60:40 composition resulted in the highest SFC due to increased airflow resistance.

The braking system is a crucial component that affects driving safety on motor vehicles, especially motorcycles. The purpose of this study was to determine how brake fluid viscosity and brake fluid pressure affect braking distance. Brake fluids A (12,001 cSt), B (11,120 cSt), and C (10,958 cSt) are three types of brake fluids that vary, along with brake fluid pressure, which ranges from 1.5 to 4.5 bar. A 7 mm bolt that is 70 mm long and drilled into the brake lever is used to limit the pressure. Based on the results of the study, braking distance is affected by fluid pressure and viscosity. With the same fluid pressure of 4.5 bar, brake fluid A is able to brake at the farthest distance of 25.01 meters, brake fluid B is able to brake at the middle distance of 23.12 meters, and brake fluid C is able to brake at the shortest distance of 21.79 meters.

The development of technology in the field of fisheries is very rapid along with facilitating human work in the field. Human work can be done by tools such as feeding catfish in ponds automatically. This job is easy to do, but problems will arise when catfish are not fed at night or are fed too late, then the catfish will eat smaller catfish so that it can be detrimental to catfish farming owners. With this background, the author created a "Catfish Feeding Control System Based on the Internet of Things (IoT) Using the Fuzzy Sugeno Method". This testing and discussion was carried out by functionally testing each component, testing the program using simulation and testing it as a whole. The results of testing the tool and taking data are expected to obtain valid data and the tool works according to its function and purpose as expected. From the results of the analysis and discussion of the research entitled "Internet Of Things (IoT) Based Catfish Feeding Control System Using the Fuzzy Sugeno Method" it can be concluded as a process of automatic fish feeding using the RTC module as a reference for catfish time three times a day with good results and the process of calculating the amount of fish feed 3 to 8% with fish weight from LOW to HIGH using Fuzzy Sugeno has worked well compared to the results of the BLYNK application.

Learning activities can run smoothly if accompanied by the availability of appropriate learning media. Learning in the Machining Technology course requires direct practical activities, for example in understanding the use of lathes. The limitations of students' mastery of knowledge when facing the teaching and learning process that tends to be lecture-oriented, causing students' lack of understanding during practice. Learning media that is less interesting causes failure in delivering material, thereby reducing students' interest in learning. This study aims to examine the effectiveness of Real Time Augmented Reality (RT-AR) Lathe media in the learning process of the Machining Technology course in the D-III Study Program, Department of Mechanical Engineering, Faculty of Engineering, Padang State University (FT-UNP). RT-AR media is designed to present interactive visualizations that describe the lathe work process in real time, so that it is expected to improve students' conceptual understanding and practical skills. The study used a quasi-experimental method with a pre-test and post-test design in two groups: the experimental group using RT-AR media and the control group using conventional learning methods. The results showed that there was a significant increase in the learning outcomes of students in the experimental group compared to the control group. In addition, RT-AR media is also able to increase students' motivation and active participation during the learning process. These findings indicate that RT-AR Lathe media is an effective and relevant learning innovation to be applied in vocational engineering education, especially in mastering lathing material.

The Tanjungpura University Hospital building is located in the city of Pontianak, which is situated on the equator and often faces the potential of lightning strikes, thus requiring the installation of an external lightning surge protection system. This study aims to design an external lightning surge protection system capable of protecting the Tanjungpura University Hospital building using the rolling sphere method. In the rolling sphere method, calculations will be made for the lightning strike distance (R), protection radius (Rp), protection area (Ax), and determination of protection angle (?). The University Tanjungpura Hospital building is at protection level IV, with a current strength of I = 16 kA and a lightning strike distance to the ground of 60.63 meters. The results obtained for using finials with the same height, hp = 1 meter, require hundreds of finials, while using a combination of finials and towers requires 68 finials. In the case of tower finials with a height hp = 10 meters, additional conductor wires are added or the catenary method is used with 14 conductor wires connecting 28 tower finials with a height of 10 meters, due to the areas outside the protection zone between these 28 final towers, necessitating the addition of conductor wires to expand the protection area of the rolling sphere method to protect the areas of the Tanjungpura University Hospital building.