This article explores the fundamental limiting speed for a nanomaterial immersed in a fluid, considering the appearance of relativistic effects at high speeds and the imposition of the Planck density as a fundamental physical limit on density. Traditionally, the speed of light in a fluid medium is considered the upper bound on the speed of any object. However, when a nanomaterial is accelerated, length contraction and relativistic mass increase significantly alter its density. By imposing the condition that the relativistic density of the nanomaterial cannot......

Keywords: Nanomaterial, Fluid, Limiting Speed, Special Relativity, Length Contraction, Relativistic Mass, Density, Planck Density.

This paper formulates the system of differential equations governing the motion of an unmanned aerial vehicle (UAV) during launch from a catapult system and its subsequent flight until reaching minimum level flight speed. Based on this mathematical model, a computational tool was developed to simulate various launch configurations. The software enables the evaluation of key motion parameters and supports the selection of appropriate input variables for launcher design, ensuring the UAV's safe and effective takeoff.

Keywords: UAV, catapult launch, flight dynamics, motion simulation, launcher design, takeoff safety, differential equations, flight stability.

Vietnam is widely recognized as a country with an economy largely dependent on agriculture. In this context, rural tourism plays a crucial role in driving economic restructuring toward the service sector, thereby enhancing the livelihoods of local communities. Beyond its economic benefits, rural tourism also contributes to the preservation of cultural identity, encourages the consumption of local products and services, fosters cultural development, upholds traditional values, and raises public awareness about the importance of protecting community-based cultural.....

Keywords: Rural Tourism, Model, Vietnam, tourism, factors.

Bacillus is one of the bacteria that has the potential as a biological agent to inhibit plant-disturbing organisms, such as Dickeya spp. The purpose of this study was to determine the inhibition of Bacillus sp. isolates isolated from the soil of the Liwa Botanical Garden related to its ability as a biological control agent against Dickeya spp. The design used in this study was a completely randomized design (CRD) with......

Keywords: Antagonist, Bacillus sp., Dickeya spp.

This study presents the design and implementation of a Particle Swarm Optimization (PSO)-based Proportional-Integral (PI) controller for a Quadratic Boost Converter (QBC) in a closed-loop control system. The PSO algorithm optimize value of the PI controller parameteres (Kp and Ki) using the Integral Time Absolute Error (ITAE) as the objective function to get the most optimize value. In this study, the PSO-based PI controller performance is tested under varying operating conditions such as different voltage reference setpoints which are 240V, 220V, and 180V with a fixed input voltage of 18V. Secondly, different load resistance value (50 Ω, 100 Ω, 200 Ω) also used to verify......

Keywords: Quadratic Boost Converter, PSO-based PI controller, ITAE objective function, Closed-Loop Control..