VNUHCM Journal of Science and Technology Development

Latest Articles

1. NATURAL SCIENCES

   A study on the optical properties of a novel flower-core photonic crystal fiber infiltrated with CCl4

   Nguyen Thi T.

   A novel design of photonic crystal fiber with a flower-core is proposed for the first time to optimize dispersion suitable for broadband supercontinuum generation. The numerical simulation of the propagation of light modes in optical fibers is computed by solving Maxwell's wave equations with the full-vector finite-difference eigenmode method. As a result, near-zero ultra-flat all-normal and anomalous dispersion was achieved with fluctuations of ±0.978 ps/nm.km in the 294 nm wavelength region and ±1.168 ps/nm.km in the 432 nm wavelength region, respectively. Furthermore, the dispersion value at the pump wavelength is about 10 times lower than in previous papers. The combination of CCl₄ infiltration into the hollow core and the air hole's size heterogeneity in the cladding also enhances the nonlinear properties of the fibers. The effective mode areas less than 2 µm² at the pump wavelength can help the supercontinuum spectrum to broaden further towards the red wavelength region. Three fibers with structural parameters Ʌ = 0.8 µm, d₁/Ʌ = 0.45, Ʌ = 0.9 µm, d₁/Ʌ = 0.5, and Ʌ = 0.9 µm, d₁/Ʌ = 0.45 are proposed for supercontinuum generation with low peak power due to the nonlinear coefficients as high as hundreds W⁻¹.km⁻¹. These fibers are a new class of optical fibers, highly efficient laser sources that replace traditional glass-core optical fibers.

   Published: 2023-10-103017-3026
2. NATURAL SCIENCES

   Toward Plasmon-Controlled Generation of the Activating Ag Hotspot Nanospheres for Quantitative SERS Analysis

   Bao N., T., G., Trang T., N., Q., Phuong P., T., Thu V. T. H.

   Through these results, we contribute to advancing the understanding of tailored nanoparticle synthesis for superior SERS performance, thus opening avenues for enhanced molecular detection in various applied analytical fields.

   Published: 2023-10-103008-3016
3. ENGINEERING AND TECHNOLOGY

   A survey of AI-based robotic process automation for businesses and organizations

   Nguyen T.,-D., Le H.,-S., Nguyen T.,-D.,-N., Lam H.,-T., Tran T.,-A., Tran Q.-T.

   This paper explores the theories and practical applications of AI, AI-based RPA and RPAn in enterprises as well as in organizations. Recent advanced and modern techniques of AI, AI-based RPA and RPA are also presented and discussed in this study. In addition, this study also presents individual and combined solutions in applying AI-based RPA for small-cap companies to leading and multinational companies. Research results show that AI-based RPA technology has very good applications to replace human activities in many different fields and industries, such as economics, administration, business, banking, marketing, and medical care.

   Published: 2023-09-302959-2966
4. ENGINEERING AND TECHNOLOGY

   AiMA - An AI-Based Mobile System to Assist College Students with Math-Related Issues

   Le T., Dang N., A., Nguyen K., Le B. N.

   As technology continues to progress, the importance and influence of mathematics in people's lives are growing. The emergence of mobile systems has brought about several benefits, such as portability, convenience, and accessibility, especially in the field of education. It is crucial to develop a mobile system that can cater not only to high school students but also to those enrolled in colleges and universities, offering solutions for basic calculations and highly specialized algorithms. To address this need, this research presents AiMA, an AI-based mobile system that assists college students with math-related issues.

   Published: 2023-09-302863-2875
5. ENGINEERING AND TECHNOLOGY

   Improving the performance of the GPS/INS integrated navigation system by using the real-time kinematic method

   Tran D., Nguyen V.-H.

   This paper presents a method for improving the accuracy of a GPS/INS integrated navigation system. Estimating the yaw angle, which is the degree of deviation from the north, is a crucial aspect in the navigation and control of autonomous robots.

   Published: 2023-09-302975-2986
6. ENGINEERING AND TECHNOLOGY

   Removing tannins and debittering brewer’s spent yeasts by Tween 80

   Nguyen T., M., X., Nguyen T., N., Nguyen T. M. N.

   Yeast extract from brewer's spent yeast cells is a promising nutrition source for many applications in the food industry and biomass production. However, because of the impurities that cause the bitter and astringent flavor attributed to hop resins during fermentation, brewer's spent yeasts in the industry have not been widely used. Contaminants have been withdrawn by using a variety of techniques. However, most reported methods have focused on removing iso-alpha acid rather than tannin, which has anti-digestive and antimicrobial properties. This study focuses on removing tannins and evaluating their impact on reusing brewer's spent yeast in biomass production.

   Published: 2023-09-302876-2887
7. ENGINEERING AND TECHNOLOGY

   Effects of pasteurization on the physicochemical, sensory properties and microbiological quality of beetroot (Beta vulgaris L.) wine during storage

   Nguyen G.

   Physical properties like pH, total dissolved solids content were significantly affected by pasteurization (higher pH and higher TTS in pasteurized samples than in unpasteurized samples) but they were not affected by storage time in this project. After fermentation, the TPC of red beetroot wine was lost but it kept unchanged after pasteurization. Vitamin C of the wine sample was lost after pasteurization only when storage. Pasteurization and 2 month-storage caused significant reduction on antioxidant capacity of red beetroot wine. Sensory quality of beetroot wine was not affected by pasteurization but it was in the case of storage. Microorganism quality of wine was acceptable for consumption. Pasteurization process is effective in increasing shelf life of red beetroot wine but does not significantly affect its nutritional and sensory values.

   Published: 2023-09-302950-2958
8. ENGINEERING AND TECHNOLOGY

   Synthesis of a self-healing polymer blend containing dynamic diels-alder and h-bond crosslinks

   Nguyen Thi M., L., Nguyen V., Nguyen Song D., A., Truong T. T.

   It is unquestioned that self-healing polymers are being applied in numerous applications due to their indiscernible advantages, such as the extension of materials’ life span. Not surprisingly, researchers throughout the world concentrate on boosting the progression of the polymer. However, it takes 24 h or 48 h for the self-healing process of polymer-based materials in manifold studies to be efficacious. This can be thought of as a problematic hurdle slowing its advancement and application. Therefore, our research was conducted in an attempt to create a blended structure through hydrogen interplay between (thio)urethane bonds and H-acceptor heterocyclic moieties.

   Published: 2023-09-302967-2974
9. NATURAL SCIENCES

   Behavioral activities of the giant water bug Lethocerus indicus (Lepeletier et Serville, 1775)

   Phommavongsa S., Vu M., Nguyen A.

   The study on behavioral activities of the giant water bug Lethocerus indicus was conducted at the Centre for Biodiversity Resources Education and Development (CEBRED), Hanoi National University of Education (HNUE). Twelve types of behavioral activity (BA) were identified and described: BA1: Horizontally floating, BA2: Diagonally floating, BA3: Swimming on the water surface, BA4: Swimming under the water surface, BA5: Respiration by extension and retraction pair of siphon, BA6: Capturing and eating prey, BA7: Vibrating legs, BA8: Openning and flapping wings, BA9: Clinging to each other, BA10: Crawling out of water, BA11: Death-feigning, and BA12: Attacking and cannibalizing each other. These 12 behavioral activities observed descended in the following order: (1) BA2 (17,24%) >(2) BA4 (16,94%) >(3) BA3 (15,75%) >(4) BA5 (14,86%) >(5) BA1 (12,18%) >(6) BA6 (11,14%) >(7) BA9 (6,99%) >(8) BA7 (2,97%) >(9) BA8 (1,34%) >(10) BA12 (0,30%) >(11) BA10 (0,15%) >(12) BA11 (0,15%). These behavioral activities can be grouped into 3 groups based on their scientific basis: Genetically (92%) >Ecologically (4.5%) >Physiologically (3.5%). This research on the behavioral activities of the giant water bug Lethocerus indicus can be considered an important scientific basis to be implemented in the raising and sustainable conservation of the species listed in The Vietnam Red Data Book since 1992.

   Published: 2023-09-302996-3007
10. ENGINEERING AND TECHNOLOGY

    Robot Gesture Control using Online Feedback Data with Multi-Tracking Capture System

    Do P., Bien M., T., Nguyen H. V. K.

    This study employs a Vicon, high-speed and accurate marker-based motion capture system to develop a wireless low-latency gesture control method that requires no additional hardware components or onboard power sources. A novel control method is designed to track a rigid-body object's motion in the workspace and translate it into robot control signals. The system comprises five main components: a host PC with Vicon software named Tracker, a set of eight Vicon Vantage V8 infrared cameras, a client PC that receives Tracker's broadcasted data over Ethernet, a robot model named youBot provided by KUKA, and a rigid-body object that acts as the gesture controller. By using an Application Programming Interface (API) called DataStream, the rigid-body object's pose (position and orientation) can be estimated and used to remotely control the KUKA youBot robot with higher accuracy and an overall reduced latency of 0.3 seconds. In comparison to existing methods based on accelerometer-based and gyroscope-based controllers, the proposed gesture controller uses a set of retro-reflective markers for tracking purposes and requires no additional hardware systems. This proposed control method proves especially beneficial for the robotics prototyping development phase, where different control mechanisms can be easily replicated and tested within the motion capture system's operating range. Additionally, the robot's odometry can also be tracked during testing, making a motion capture system a valuable tool for evaluating motion control methods.

    Published: 2023-09-302917-2929