This study evaluates and compares the effectiveness of friction stir welding on aluminium and copper alloys with the aim of improving the strength of the resulting joints. The rotary friction stir welding method was chosen for its ability to produce high-quality joints with minimal deformation. This study explores various welding parameters, such as rotating speed, welding speed, and tool design, and their impact on the mechanical properties of the joint, including tensile strength, hardness, and microstructure of the weld region. The findings show that the optimum parameters for aluminium and copper alloys differ significantly: the tensile strength of aluminium is around 240 MPa, while copper joints require careful adjustment to avoid defects, reaching around 220 MPa. Aluminium showed improved joint strength with higher rotating speed and welding speed parameters, while copper required more precise parameter adjustments to prevent cracking and other defects. The results of this study provide practical guidance for selecting appropriate rotary friction welding parameters to optimize joint strength in aluminium and copper alloys, which can enhance the application of these materials in industry.

The depletion of petroleum reserves as the basic raw material for gasoline production has driven studies into alternative fuels. One of the alternative fuels is alcohol, both ethanol and methanol. Due to their liquid form and physical-chemical properties similar to gasoline, small modifications to the engine are required. This paper will explain the effect of using a mixture of gasoline (in this case, RON 98 gasoline with methanol or methanol on engine performance and emissions. The fuel mixtures are as follows: G100, E10, E20, E30, M10, M20, M30. AVL Boost simulation software was used as a tool for 1-dimensional engine modelling, where the modeling is based on engine testing with G100 fuel. The results show that with increasing ethanol-methanol composition, torque and power decrease, and SFC increases. On the emission side, CO, CO2, and HC were decreased and NOx increased.

Indonesia is currently developing a Medium Altitude Long Endurance Unmanned Aerial Vehicle (MALE UAV). This vehicle is used as a platform to meet the growing need for aerial surveillance in response to increased threats in border areas, terrorism, and the theft of natural resources, such as illegal logging and illegal fishing. This book chapter will discuss the readiness of the technology innovation ecosystem assessed using a national innovation system concept approach, technology innovation readiness, and efforts to increase the local content level (TKDN) of the MALE UAV. The results indicate that several framework conditions still need to be developed, including establishing certification testing institutions. For technology innovation readiness, the findings show that the domestic manufacturing industry is sufficiently prepared for the airframe component, while the Flight Control System (FCS), Ground Control System (GCS), Communication System (CS), and Weapon System (WS) components still require strengthening. Efforts to increase the local content can be pursued by strengthening the industrial structure and engineering design capabilities.

!Monitoring low levels of water contamination in biodiesel is important because moisture levels above 500 ppm trigger the biodiesel to become microbially unstable, and corrode. In this study, we detail a frequency-optimized phase-shift capacitive sensing technique that is able to identify sub–1000 ppm levels of moisture in biodiesel through the use of dielectric-dependent phase variations. A semi-cylindrical capacitive sensor was constructed and tested with differential dual-channel excitation. Frequency sweeps within the 1–120 kHz range showed peak sensitivity at 30 kHz. At this frequency, the sensor captured a linear response (R² ~ 0.959) within the 304–712 ppm range, demonstrating a response rate of 4.1 mdeg/ppm, a resolution of ~100 ppm, and an LOD of 168 ppm. The system exhibited a stable operation with ~0.2% relative standard deviation, demonstrating its robustness. These results suggest excitation frequency has significant impact on capacitive sensing design and prove that this is an effective option for real time in-situ biodiesel quality monitoring. The methodology has broader applications for the assessment of other dielectric based liquids.