Journal of Applied Science and Technology

EFFECT OF GRAPHENE ON STRENGTHENING MECHANISM OF CuTa/GRAPHENE NANOCOMPOSITES

Thi-Quy Vu — 2025-03-12

Tensile behavior of CuTa/Graphene nanocomposites through molecular dynamics simulations is revealed in this study. The influence of graphene on the mechanical performance of the amorphous CuTa matrix is analyzed by varying the graphene volume fraction. The results indicate that the incorporation of graphene significantly enhances tensile strength, Young’s modulus, and failure strain, contributing to improved material toughness and stiffness. The increased mechanical stability of the composites demonstrates graphene’s effectiveness in reinforcing amorphous alloy. Shear strain distribution analysis reveals that deformation primarily originates at the graphene-amorphous interface, leading to the formation of shear transformation zones. As the graphene content increases, the composite exhibits greater resistance to plastic deformation, with stress concentration localized around the graphene layers. The redistribution of stress and strain near the graphene layers indicates their critical role in strengthening the amorphous matrix. Additionally, atomic displacement analysis shows that graphene modifies the deformation pathways, leading to shear sliding and an altered strain distribution.

STUDY ON THE ELECTRICALLY ASSISTED HEATING PROCESS IN SINGLE POINT INCREMENTAL FORMING OF AA1050 ALUMINUM ALLOY

Luyen The Thanh — 2025-03-12

This paper presents an integrated electro-thermal model for the single point incremental forming (SPIF) process of AA1050 aluminum. A three-dimensional model of the heating system was developed, incorporating Joule heating and heat conduction in solids. Relevant heat transfer coefficients were identified and computed. The model also integrates the current switching mechanism used in practical heating control systems. Simulations were conducted for three target temperatures: 200°C, 250°C, and 300°C. The resulting temperature distributions within the system and on the forming blank were obtained. Temperature values at multiple locations on the blank were extracted to evaluate spatial variation. Results indicate that temperature oscillations occur due to the periodic switching of electric current. These findings provide valuable insights into thermal behavior during SPIF of AA1050, enabling the design of more effective heating control strategies to achieve the desired temperature range.

EFFECT OF COATING THICKNESS ON MECHANICAL BEHAVIOR AND MICROSTRUCTURE OF CuCrCoFeNi COATING ON Cu CRYSTALLINE SUBSTRATE

Thanh-Nga Trinh — 2025-03-17

This study uses molecular dynamics simulations to explore the mechanical behavior of high-entropy alloy CuCrCoFeNi coatings on Cu crystalline substrates during nano scratching, with a focus on detailed analysis of the micro-deformation mechanisms and the influence of coating thickness on the mechanical properties. Through simulations performed on samples with coating thicknesses ranging from 10 Å to 30 Å, significant variations in the mechanical parameters were observed: the average tangential force and normal force increased with the coating thickness, while the friction coefficient decreased markedly at thicker coatings. Notably, the maximum pile-up height in the deformation zone decreased with increasing thickness, reflecting a significantly improved resistance to surface deformation. In-depth analysis of the stacking fault distribution, dislocations, shear strain, and post-scratching surface morphology provided insights into the deformation mechanisms at the atomic scale. These results not only elucidate the mechanical properties of the high entropy alloy CuCrCoFeNi but also confirm the outstanding potential of this material in engineering applications requiring high wear resistance and mechanical strength.

BUILDING A SYSTEM FOR MEASURING MECHANICAL PROPERTIES AT VARIOUS POINTS OF A CAR SEAT CUSHION

Xuan Tien Tran — 2025-03-20

This paper focuses on presenting a system for measuring the mechanical properties of a car seat cushion. The mechanical system includes a support frame that securely holds the car seat in place and a 3-axis CNC motion mechanism that enables the force sensor to move flexibly and accurately to the required measurement positions, as well as to follow the desired movement trajectories. The mechanical system is designed using Inventor software and experimentally fabricated.

The servo motor control system utilizes a PLC controller and TIA Portal software to ensure precise positioning and movement along the desired trajectory. Data measurement and acquisition are carried out using the NI USB 6001, with an interface programmed in LabVIEW, enabling reliable data collection and easy control. The collected data is further processed using MATLAB to generate force-displacement curves, representing the mechanical properties of the seat cushion at different measurement points. Finally, some measurement results are analyzed and evaluated to demonstrate the system’s reliability.

INVESTIGATION OF SURFACE ROUGHNESS OF STAINLESS STEEL- INOX 304 DURING ELECTROPOLISHING WITH ADDITIVES

Nguyen Van Thoai — 2025-03-25

The electropolishing method has been widely applied to enhance the surface smoothness of stainless steel materials. However, safety concerns during the polishing process are of particular importance, as the electrolytes used typically contain high concentrations of strong acids, such as sulfuric acid (H₂SO₄) at 35 wt.% and phosphoric acid (H₃PO₄) at 50 wt.%. Therefore, this study focuses on determining the optimal composition of electrolyte components and appropriate polishing conditions to improve surface treatment efficiency while ensuring workplace safety. The results identified a suitable electrolyte solution and an optimal polishing temperature range of 30–50°C for stainless steel 304. Specifically, when adding the chromium oxide (CrO₃) additive, despite reducing the H₂SO₄ concentration to approximately 20 wt.%, the surface roughness achieved was significantly low (Ra = 0.075 µm). Furthermore, by incorporating the Glycezyl additive, even though the H₂SO₄ and H₃PO₄ concentrations were simultaneously reduced to 24. wt% and 18. wt%, respectively—considerably lower than those used in previous studies—the achieved surface roughness remained comparable, with Ra reaching 0.118 µm.

A STUDY ON THE EFFECT OF TECHNOLOGICAL AND GEOMETRIC PARAMETERS ON THE WALL THICKNESS OF SPCC CYLINDRICAL CUPS IN TWO-STAGE DEEP DRAWING PROCESS

Luyen The Thanh — 2025-03-25

This paper investigates the two-stage deep drawing technology of SPCC cylindrical cup products through simulation and experimental methods. The simulation model provides good compatibility with experimental results. Subsequently, an analysis of the impact of technological parameters such as the blank holder force (Ff), geometric parameters including the punch corner radius (Rpf), die corner radius (Rdf), and the gap between punch and die (wf) on the thickness distribution of the cylindrical cup was performed. The optimal parameters were selected as Rdf = 8 mm; Rpf = 6 mm; wf = 1.2 mm; Ff = 8 tons in the first forming stage, yielding the best thickness distribution. Finally, the Taguchi experimental design method and Analysis of Variance (ANOVA) were employed to study the effects of the punch-die gap and blank holder force on the thickness distribution of the final product. The results show that the blank holder force has the most significant effect, while the punch-die gap has a smaller impact, with their respective influence percentages being 72.91% and 23.59%; the effect of noise factors was 3.5%. The optimal technological parameter set for minimizing product thickness variation was A3B2, corresponding to WS = 1.4 mm; and FS = 9 tons. The findings of this study provide significant contributions to die design, reducing experimental costs, and improving the quality of two-stage deep drawing products.

AVALUATION OF THE TENSILE STRENGTH AND ELONGATION OF SILK AND NYLON SURGICAL THREADS ACCORDING TO THE LENGTH

Hoang Thanh Thao — 2025-03-12

The article compares the tensile strength and elongation at break of two commonly used nonabsorbable surgical sutures for skin, soft tissue, and surgical wound closure techniques: Silk (natural) and Nylon (synthetic), both with a suture size of 3/0, in three conditions: without a needle attached, with a needle attached, and after knotting. The article also presents the relationship between tensile strength and elongation at break of the sutures under these conditions across different suture lengths used for stitching (experimented with suture lengths of 115 mm, 120 mm, 125 mm, 130 mm, and 135 mm). The research results provide guidance for selecting appropriate sutures according to tissue types or specific suturing technique requirements, thereby supporting clinical decision-making regarding the choice of surgical sutures in medical practice.

DETERMINING THE EFFECTS OF FABRIC STRUCTURE PARAMETERS ON SOME PHYSICAL AND MECHANICAL PROPERTIES OF KAKI FABRIC USING CVC 65/35 YARN

Gian Thi Thu Huong — 2025-03-25

In the structure of woven fabrics, the composition of raw materials is an important factor in determining the properties of the product. CVC khaki fabric is quite commonly used in labor protection products, to take advantage of the optimal properties of cotton and PES fibers, in which the proportion of cotton fibers is higher than that of polyester fibers. In this paper, experimental research was conducted to determine the changes in some physical properties of the fabric such as tensile strength, relative elongation, abrasion resistance, and wrinkle resistance of some domestically produced CVC 65/35 khaki fabric samples, when changing some other structural parameters of the fabric. The results showed that fabrics with higher fiber density using lower yarn counts have better tensile strength and abrasion resistance, suitable for labor protection products. As for fabrics with lower fiber density, using higher yarn counts, the fabric is softer and has better wrinkle resistance, suitable for office wear.

THE BEHAVIOR OF SOLUTIONS TO PARTIAL NEUTRAL FUNCITONAL DIFFERENTIAL EQUATIONS

Nguyen Thi Thu Hang — 2025-03-28

In this paper, we analyze the behavior of solutions to partial neutral functional differential equations

under the conditions that the family of linear operators , defined on a Banach space X , generates an evolution family which has an exponential dichotomy on J = ⁺or J = , and the nonlinear term Φ satisfies the -Lipschitz conditions, i.e., , where (t) belongs to some admissible function spaces. Our main method is based on the admissibility of function spaces.

RELATIONSHIP BETWEEN STABLE MANIFOLDS AND UNSTABLE MANIFOLDS FOR FINITE DELAY PARTIAL FUNCTIONAL DIFFERENTIAL

Nguyen Thi Hanh — 2025-03-26

Based on the equation

we construct a homomorphism from the intersection of two integral manifolds to a subspace of the phase space . Here, the evolution family is generated by the family of linear operators in the Banach space X. The delay term h(t, z_t) satisfies the ψ-Lipschitz conditions, i.e., , where ψ(t) belongs to some classes of admissible function spaces. Our main method is based on the admissibility of function spaces.

SIMULATION STUDY OF ELECTRONIC FUEL INJECTION MOTORCYCLE ENGINE USING E0, E30, AND E50 FUELS

Pham Huu Tuyen — 2025-03-26

Nowaday, Vietnam has approved a plan to use biofuel with a high ethanol blend as fuel for vehicles. Since ethanol has different properties from regular gasoline, biofuel with a high ethanol content will affect engine performance. To increase the use of ethanol, research is needed to study the impact of biofuel with more than 10% ethanol. This paper presents a study on the performance of a Honda Lead 110 motorcycle engine with electronic fuel injection (FI) using E0 (RON 92 gasoline), E30 (70% RON 92 gasoline - 30% ethanol), and E50 (50% RON 92 gasoline - 50% ethanol). The engine was simulated using AVL Boost software and calibrated with test results from a test bench using E0 fuel. The study evaluates engine performance in two cases: keeping the original settings and adjusting the fuel injection and ignition timing.

RESEARCH ON THE CHANGE REGIME OF THE K-25-90 STEAM TURBINE

Truong Ngoc Tuan — 2025-03-18

The article studies the increase and decrease of steam flow G0 into the turbine, then parameters such as: useful heat of the stage, actual speed of steam flow out of the nozzle groove, relative speed of steam flow into the blade array, energy of steam flow into the stage, especially internal capacity of the stage, ... also change according to the corresponding steam flow.

SYNTHESIS OF ACTIVATED CARBON FROM LONGAN PEEL AND SEED USING ZNCL₂ AS AN ACTIVATING AGENT

Nguyen Trong Nghia — 2025-03-27

In this study, activated carbon (AC) was successfully synthesized from longan peel and seed – an abundant agricultural byproduct – using chemical activation with ZnCl₂. The influence of activating agent concentration, activation temperature, and heating time on the adsorption capacity was investigated, revealing that these parameters significantly affect the quality of the final product. The optimal conditions were determined to be 50% ZnCl₂ concentration, activation temperature of 500 °C, and heating time of 90 minutes. The resulting activated carbon exhibited low moisture content (~4.36%), ash content below 6%, nearly neutral pH (~6.7), an iodine number of approximately 714 mg/g, a methylene blue adsorption capacity of ~236 mg/g, and a surface area of 896.52 m²/g. SEM, XRD, and N₂ adsorption–desorption isotherm analyses indicated a well-developed mesoporous structure and characteristic amorphous nature of the material. These results demonstrate that activated carbon derived from longan peel and seed holds great potential for wastewater treatment applications and highlights an effective approach to valorize agricultural waste into environmentally friendly adsorbent materials.

EXPANSION OF ENROLLMENT AREAS - CURRENT OPPORTUNITIES AND CHALLENGES FOR HUNG YEN UNIVERSITY OF TECHNOLOGY AND EDUCATION

Luu Van Tan — 2025-03-28

This article analyzes the opportunities and challenges in expanding the enrollment area of Hung Yen University of Technology and Education. Expanding the enrollment area is not only an important strategy to attract more students from other provinces and cities, but also helps to enhance the position and competitiveness of the school. The article will clarify opportunities such as increasing the diversification of student resources, improving the quality of enrollment, and enhancing brand recognition. At the same time, challenges are also mentioned, including difficulties in accessing the enrollment market, investment requirements in technology and human resources, and necessary changes in communication strategy. Specific models and solutions will be proposed to help the school effectively implement the expansion of enrollment areas in the current period.