Tạp chí khoa học và công nghệ

This study investigates the mechanical properties and deformation behavior of ZrCu alloy coatings on a Cu crystal surface using molecular dynamics (MD) simulations. The research focuses on the response of Zr80Cu20 alloy coatings under varying scratching and impact velocities, employing the LAMMPS package with a spherical indenter to simulate scratching processes. The simulations reveal that increased scratching velocities lead to higher frictional forces and shorter steady-state phases. Similarly, higher impact velocities result in more pronounced shear strain, stress distribution, and temperature rise within the coating. Additionally, the findings indicate that velocity significantly influences the mechanical response of ZrCu alloy coatings, providing insights into their potential applications in high-performance industries where material durability and stress resistance are critical.

This article investigates the material structure and deformation behavior of the Ni70Co30 alloy film on a Ni(001) substrate using the molecular dynamics (MD) simulation method. The simulations performed include deposition, annealing, and indentation. The study also examines the effect of temperature on the structural changes of the alloy film. The results show that higher temperatures lead to a decrease in the force required for indentation. Additionally, increasing temperature enhances the deformation behavior and structural changes of the Ni70Co30/Ni material. Notably, high temperatures influence the formation and development of dislocation in the Ni70Co30 alloy film on the Ni(001) substrate.

This paper analyzed C4.5, Bayes algorithms for classification and the prediction problems. The classification criteria based on the confusion matrix are used to evaluate the classifier and predicted results. Weka software program was used to test the proposed classifier and predicted data.

We have successfully synthesized Polypyrrole (PPy) films directly formed on the surface of theelectrodes by a facile route of vapor phase polymerization method, with the oxidant and dopant agent areferric chloride (FeCl3 ). The surface morphologies and chemical structure of samples were considered byscanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FT-IR). The sensitivitiesof sensing were studied based on resistance change to the concentration of the NH3 gas (100 - 400 ppm) atroom temperature. These results demonstrated that the response of gas sensor has been strongly affectedby surface morphologies of material membrane. This work shows that PPy films were fabricated from thevapor phase for a lots promising in applications of NH3 gas sensors operating at room temperature

Currently, most gear in the actuator are made by traditional methods such as bulk forming from block billet and then cutting for finishing. Such manufacturing methods often lead to material wastes due to cutting out of a large about 30% amount of excess processing. To save material and improve production efficiency, we can choose tube billet for bulk forming. However, when using bulk forming with tube billet, it should be calculated carefully to avoid being of instability and appearing of folding defects in workpiece. This article presents the research on forming process of the coupling detail using methods numerical simulation and based on obtained results to determine the suitable geometry of tube billet for the forming in closed die.

The fixed point theory has been applied to the optimal design of dynamic vibration absorbers parameters for undemped structure. With damped structure the installation of many dampers the same is often resolved by numerical methods. This paper uses the equivalent of the damped structure to undemped structure and the fixed point theory to optimize the parameters of the dynamic vibration absorbers. The approximate analytical expressions of the optimal damping ratio and the optimal tuning ratio for the same MTMD system are given. The results are applied to reduce vibration for the diesel engine model. The frequency response of MTMD and single TMS system is compared has shows that with the same mass ratio, the efficiency of MTMD systems and single TMD is similar. Time response of the primary system without TMD and with TMD clearly demonstrate the efficiency when using MTMD to reduce vibration for machines and structure.

This paper presents experimental studies on the influence of some technological factors on cutting tool wear when machining steel 45 on high speed 3-axis CNC machines. Experiments were conducted on the Super MC 500 high-speed milling machine. The author has used the experimental planning method to construct empirical formulas describing the influence of the cutting speed technology parameters, the amount of knife running to the back of the knife. These rules are the basis for determining the right technology parameters, thereby improving the durability of the cutting tool, optimizing the cutting process.

The robust development of smart medical applications and the powerful connectivity of next-generation mobile networks posed significant challenges concerning data accessibility, security, privacy, and e-health data collection for the Internet of Medical Things (IoMT) applications. This work offers a comprehensive vision of the stage-of-the-art IoMT applications on aspects of architecture, applications, and processing challenges of large-scale medical data. Then, we highlight the advantages of fusing edge computing into IoMT applications. Finally, we discuss ongoing issues, challenges, and feasible study directions for future smart IoMT applications.

The International Union of Railways has decided to migrate railway communication technology from being GSM-based to LTE-based or LTE-R. As a leading country in LTE space, South Korea will launch the train control system based on LTE by 2016. To ensure the most reliable train operation in this system, a fully duplicated network structure with overlaid radio cells is needed. Existing methods and results often rely on a single network structure setup. Thus, in this paper, we introduce the design of an LTE-R train control communication with a duplicated network structure. We propose two different network structures with fully-overlapping cell arrangement and with partly overlapping cell arrangement, respectively for the system and discuss major problems, including handover and inter-cell interference.

Over the past few years, start-up is a matter of intense concern in Vietnam. To promote start-ups, the state creates business eco-systems and business incubators in which university students are the center of these incubators. This article explores the theoretical issues surrounding start-ups, analyzes the factors that influence the success of students in the start-up process, and suggests some issues that students need to prepare to start a successful business. The research results are useful suggestions for schools and students organizing activities related to the process of training, learning, scientific research and extracurricular activities in order to provide students knowledge and skills during their start-ups.