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..

This study investigates the numerical modelling (using TRNSYS software) and thermal performance of a Phase Change Material (PCM)-lagged thermal storage tank (TST) for domestic hot water systems. A computational model was developed to simulate heat retention in PCM-lagged tanks using paraffin, PEG 4000, and sodium thiosulphate as storage media. Results indicate that PCM-lagged tanks significantly outperform conventional insulated tanks, maintaining water temperatures above 52.31°C after 24 hours compared to 24.65°C in non-PCM tanks. Sodium thiosulphate emerged as the most cost-effective PCM, offering optimal thermal stability, while PEG 4000 demonstrated superior......

Keywords: Phase Change Material, Thermal Storage Tank, Domestic Hot Water, TRNSYS.

Presented herein is the design and implementation of an sEMG-based control system for a robotic leg, utilizing surface electromyographic signals recorded from the quadriceps muscles. The developed system integrates four key functional components: (1) acquisition and preprocessing of sEMG data; (2) extraction of the root mean square (RMS) as a measure of muscle contraction intensity; (3) transformation of signal features into actuator control signals; and (4) the mechanical design of a biomimetic robotic leg. The knee joint actuator is controlled based on the RMS value, enabling the reproduction of natural and accurate lower limb flexion and extension. Initial experimental findings indicate the system's capacity for prompt and stable response to user neuromuscular input, suggesting its applicability in areas such as rehabilitation robotics, assistive devices, and human-computer interaction.

Keywords: EMG signals, robotic leg, control, RMS, prosthetic systems.

This research endeavors to investigate and develop a speed regulation system for three-phase asynchronous motors, a prevalent actuator in industrial applications. The methodology employed herein leverages a Proportional-Integral-Derivative (PID) control algorithm implemented on a Siemens S7-1200 Programmable Logic Controller (PLC) platform to achieve precise, stable, and dynamically responsive speed control under fluctuating load torques.The impetus for this study arises from the escalating demand for enhanced operational efficiency and energy conservation within industrial automation paradigms......

Keywords: PID,3-phase induction motor, PLC,speed control, inverter.

The topic researches on customer satisfaction with service quality at Da Nang Food Tour Festival 2025.Survey data collected from 450 tourist from over the world. The proposed research model and measurement scale were formed based on the research results of domestic and foreign authors and consultation with experts. Research results show that the factors affecting visitor delight are: reliability, tangibility, empathy, responsivenessand assurance. From the research results, the author makes a number of recommendations for administrators in tourism in Da Nang.

Keywords: Customer satisfaction, service quality, Da Nang.

This article introduces one of the teaching methods that is very meaningful in enhancing the activeness of learners: applying a combination of some active teaching methods to teach the chapter "Electromagnetic Induction" of the General Physics subject at the Vietnam - Korea University of Information and Communication Technology. With this method, students are almost completely proactive, self-reliant in searching and receiving knowledge. Through the article, the author presents that the class is divided into groups of students, each group takes on a certain amount of knowledge in the chapter. The lecturer guides and requires the groups to manufacture, assemble......

Keywords: Active teaching method; Electromagnetic induction, Creative.

Nowadays, the increasing complexity and sophistication of Distributed Denial of Service (DDoS) attacks necessitate the development of advanced practical training systems. These systems are essential for students majoring in Network and Information System Security to gain hands-on experience in detecting, preventing, and thoroughly analyzing DDoS attacks. Traditional training environments are often limited in scope, lack scalability, and fail to incorporate comprehensive analytical tools.......

Keywords: Network and Information System Security, DDoS Attack, Practical Cybersecurity Training, Intrusion Detection and Prevention, SIEM, Attack Simulation.