This study aims to investigate the effect of rice husks’ particle size on resin-based brake pad performance (i.e. compressive strength, puncture strength, mass loss, wear rate, friction coefficient, and heat resistance). Bisphenol A-epichlorohydrin and cycloaliphatic amine were mixed to form resin and used as the brake pad's base material. In the experiment, rice husk with a specific particle size (i.e., 250, 500, dan 1000 μm) was added to the resin. Rice husk has received considerable interest due to its lignin, cellulose, and silica content, making it suitable as friction material due to its ceramic-like behavior. The experimental results showed small rice husk particles improved compressive strength, puncture strength, and bulk density. This can be obtained from the analysis of the maximum compressive strength for brake pad supported by particles with sizes of 250, 500, and 1000 μm having values of 0.238; 0.173; and 0.144 MPa, respectively. In contrast, large particles formed coarse surfaces and pores, decreased mass loss rate, and improve friction properties (i.e. wear rate, friction coefficient). The friction coefficient values of brake pad supported by particles with sizes of 250, 500, and 1000 µm were, respectively, 0.2075; 0.2070; and 0.3379. Particle size affected interpacking, interfacial bonding, pores number and size, thermal softening, mechanical properties, and friction properties of the brake pad. Comparison between the prepared resin-based and commercial brake pad was also done, confirming the utilization of agro-waste as a potential alternative for friction material in the brake pad.

The objective of this study was to investigate isotherm adsorption of carbon microparticles from pineapple peel waste. Carbon microparticles were prepared by carbonizing pineapple peel waste at 215-250°C and grinding using a saw-milling process. To investigate adsorption properties of carbon microparticles, experiments were done by evaluating adsorption of curcumin (as a model of adsorbate) in the ambient temperature and pressure under constant pH condition. To confirm the adsorption characteristics, carbon particles with different sizes (i.e., 100, 125, and 200 ?m) were tested, and the adsorption results were compared with several standard isotherm adsorption models: Langmuir, Freundlich, Temkin, and Dubinin- Radushkevich. To support the adsorption analysis, several characterizations (i.e., optical microscope, sieve test, and Fourier transform infrared analysis) were conducted. The adsorption test showed that the adsorption profile is fit to the Freundlich model for all variations, indicating the multilayer adsorption process on heterogeneous surfaces and interactions between adsorbate molecules. The results from other isotherm models also confirmed that the adsorption process occurs physically via Van der Waals force in binding adsorbate on the surface of adsorbent.

The rise of wing-rock motion in delta-wing aircraft has an adverse effect on the manoeuvrability of aircraft and it may result in its crash. This study presents a finite-time control design to tackle the dynamic motion due to the Wing-Rock effect in delta-wing aircraft. The control design is developed based on the methodology of Super Twisting Sliding Mode Control (STSMC). The Lyapunov stability analysis has been pursued to ensure asymptotic convergence of errors and to determine the finite time. The design of STSMC leads to the appearance of design parameters, which have a direct impact on the dynamic performance of the controlled system. To avoid the conventional tuning of these parameters and to have an optimal performance of the proposed controller, a modern optimization technique has been proposed based on Wale Optimization Algorithm. A comparison study between optimal and non-optimal finite-time super twisting sliding mode controllers has been established and their effectiveness has been verified via numerical simulation using MATLAB programming format.

At present, most countries all over the world are being hard hit by the COVID-19 pandemic and some even are being hit harder than others. This condition has caused widespread disruption of the economic, social, and educational systems in those countries.  Under these conditions, transportation systems also need to be considered. There are problems of distribution of drugs and kits of test equipment to areas far from large cities in the center of the corona pandemic due to access difficulty. Remote locations, being difficult to reach, make the distribution of drugs and equipment for rapid testing uneven so that the recovery rate of patients in the area has a low percentage. Meanwhile, it is essential to ensure the availability of drugs and rapid test equipment in every public health center in all directions of Indonesia. One possible solution is the use of drones to distribute these things to areas that are difficult to reach. This solution is expected to at least improve healing and reduce mortality for patients infected with COVID-19 in remote areas.

The surveillance and security of areas such as home, laboratory, office, factory, and airports, are important to prevent any threatening to human lives. Mobile robots are proven their effectiveness in a large number of applications, especially in hazardous areas where they can be remotely controlled by humans to accomplish certain tasks. This research paper presents a design and implementation of a mobile robot for surveillance and security applications. The main objective of the design is to lower the cost and the power consumption of the mobile robot which accomplish using low-cost open-source hardware such as Arduino and Raspberry Pi. The robot is connected wirelessly via a low-power ZigBee module to the control station to allow the operator for controlling the mobile robot motions and monitoring the physical events in the environment where the robot is used.  Sensors such as camera, temperature, and range are embedded in the robot to sense and monitor human motion, the room temperature, and the distance of the surrounding obstacles. The testing of the implemented mobile robot shows that it can run continuously for approximately 6.5 hours at a motor shaft speed 25 rpm of unlit the need to recharge the battery.