International Journal of Aviation Science and Engineering - AVIA

Active Vibration Control of a Flexible Spacecraft Structure

2025-05-03T05:35:09+07:00

In this paper, the spacecraft that evaluated has two motion mode, rigid body mode and flexible mode and it is
operated in low earth orbit. The rigid body mode is related to the attitude of spacecraft and flexible mode is related
to vibration that occurs on the spacecraft structure. The vibration that occurs on the spacecraft structure may cause
performance degradation during operation. Hence, the active control vibration is applied to overcome the problem
due to the vibration phenomenon on spacecraft. The active control system was designed by using two methods,
Pole-Placement Method and Linear Quadratic Regulator (LQR) Method, and those two methods are solved by
using numerical method. The result of Pole-Placement Method shows the vibration is reduce in less than 0.5 unit
of time. Whereas, the most suitable control parameter input based on the LQR Method could reduce vibration in
less than 8 unit of time. The LQR method provides more parameter variation; thus, the system could be controlled
and adjusted due to its design requirement. Based on the LQR Method when the attenuation time is 8 unit of time,
the energy required by the actuator is 84% less than that of the Pole-Placement Method.

Numerical Simulation of Droplet Behavior under Varying Density Ratios Using Finite Volume-Front Tracking Method

2025-05-10T09:09:10+07:00

The study of droplet dynamics is very important to understand the mechanism of heat, mass, and momentum transfer in two phases. One approach to studying this phenomenon is through numerical simulation. The front tracking method is one of the techniques often used in numerical simulation of droplets to handle phase interactions in multiphase flows. This study aims to study the characteristics of droplets when they collide with surfaces with varying density values. The modeling used in this study is an interface diffusion approach using 2 types of fluids that have different properties. The domain used is Square Box-Staggered Grid. The software used is MATLAB R2024a. The results of the study indicate that the density ratio has a significant effect on the spreading factor, apex height, spreading velocity and pressure.

Synergy Analysis of Biomass and Polystyrene Co-Pyrolysis Products Using a Microwave-Assisted

2025-05-10T09:03:38+07:00

This study aims to synergize pyrolytic oil products obtained through co-pyrolysis of biomass (palm shells) and food packaging waste (polystyrene) with the addition of a mixture of natural zeolite catalysts and CaO using a microwave-assisted. The main raw materials of palm shells and polystyrene are mixed with a ratio of 1:1 plus coconut charcoal as absorber 50% of the total main raw materials, and the catalyst mixture ratio is 1:1. This study used microwaves as a reactor with various power variations, namely 300 watts, 450 watts, 600 watts, and 800 watts. Analysis of pyrolytic oil products in the form of calorific value using a bomb calorimeter and chemical composition using mass spectrometry. The results showed that the optimal power to use was 600 W, with a calorific value (HHV) of pyrolytic-oil of 40.10 MJ/Kg, and a percentage of compound content of 99.19% dominated by aromatic compounds 17.83% and aliphatic 76.93% with high hydrocarbon content.

Sintering Behavior of Lampung Limestone-Based Hydroxyapatite for Use as a Bone Filler Material

2025-05-09T16:51:19+07:00

Limestone from Mount (Mt.) Beranti, Lampung Province, contains 97.43% calcium carbonate (CaCO₃), making it a suitable natural precursor for synthesizing hydroxyapatite (HA). HA is widely utilized as a bone tissue filler, particularly in treating osteoporosis. In this study, CaCO₃ was processed using ball milling at 300 rpm for durations of 2, 3, and 4 hours, followed by sintering at temperatures of 600°C, 800°C, and 1000°C for holding times of 2, 3, and 4 hours. FTIR analysis using the hydrothermal method on calcined limestone powder revealed characteristic peaks corresponding to phosphate (PO₄³⁻) at 1025.45 cm⁻¹, calcium oxide (Ca–O) at 1413.59 cm⁻¹, and hydroxyl (O–H) at 3030.33 cm⁻¹, which closely resemble those found in commercial HA. SEM-EDX analysis at 1000°C for 4 hours showed a homogenous microstructure, with EDX results indicating the highest concentrations of calcium and phosphate after milling for 2 hours. Vickers hardness testing confirmed the highest hardness value was also achieved at 1000°C for 4 hours. Overall, the FTIR, SEM-EDX, and microhardness results demonstrate enhanced properties of HA, supporting its effectiveness as a material for filling porous bone tissue.

Keywords: Limestone; Hydroxyapatite (HA); Calcium Carbonate (CaCO₃); Bone Filler

Analysis of Low Noise Amplifier Design for 1 GHz IoT Water Monitoring System

2025-05-10T08:44:29+07:00

The Internet has greatly accelerated the development of machine-to-machine communication technologies, enabling the remote monitoring and control of water treatment processes. A key example of this is the Internet of Things (IoT)-based Water Quality Management (WQM) systems, which utilize wireless sensors to monitor environmental parameters in real-time. These sensors are connected to a central gateway that aggregates and transmits data, facilitating timely interventions when water quality deviates from standards. The use of wireless communication minimizes installation challenges and environmental disruption. However, signal attenuation, particularly in Ultra High Frequency (UHF) bands over water, presents a challenge due to factors like temperature variations, antenna height, and surface roughness. UHF signals, while favorable for IoT applications due to their high data throughput and low power consumption, face propagation limitations over water surfaces. Despite these challenges, UHF's ability to penetrate structures and support large networks makes it a viable choice for IoT in aquatic environments. This paper explores the design of low noise amplifiers (LNAs) to mitigate signal attenuation in IoT systems for WQM, with a focus on enhancing signal integrity while maintaining low power consumption. By optimizing LNAs, the study aims to address the unique communication challenges posed by water environments, ensuring reliable and efficient operation of WQM systems