Procedure for performing a fixed microscopic specimen of the gonads of fish

This study aims to provide a procedure for performing microscopy in fish gonads. Specimens used in this study were the ovaries and testes of fish collected in the Mekong Delta from April to July 2022. Organs at five different stages for each sex (ovary diameter from 1.16 cm in stage I to 4.04 cm in stage V; testis diameter from 0.42 in stage I to 2.39 in stage V) were studied in this procedure. The results showed that both ovaries and testes needed to be fixed at 4% formol for 24 h and under running water for eight hours. Ovaries and testes were then immersed in 500 ethanol for 24 h to initiate dehydration. Results showed that the time for dehydration and paraffin infiltration was longer in the ovary (26 to 55 h across stages) than in the testis (25 to 26 h across stages). The mean staining time of the ovary was 1.5 min (stage I) to 3.5 min (stage V) in Hematoxylin and 50 s (stage I) to 140 s (stage V) in Eosin. Whereas the staining time of testis was shorter, 1 min (stage I) to 3 min (stage V) in Hematoxylin and 30 s (stage I) to 90 s (stage V) in Eosin. This study provides a reference for further studies on the histological structure of fish gonads. These results could be applied to fish species inside and outside the Mekong Delta

A Fuzzy LQR PID Control for a Two-Legged Wheel Robot with Uncertainties and Variant Height

This paper proposes a fuzzy LQR PID control for a two-legged wheeled balancing robot for keeping stability against uncertainties and variant heights. The proposed control includes the fuzzy supervisor, LQR, PID, and two calibrations. The fuzzy LQR is conducted to control the stability and motion of the robot while its posture changes with respect to time. The fuzzy supervisor is used to adjust the LQR control according to the robotic height. It consists of one input and one output. The input and output have three membership functions, respectively, to three postures of the robot. The PID control is used to control the posture of the robot. The first calibration is used to compensate for the bias value of the tilting angle when the robot changes its posture. The second calibration is applied to compute the robotic height according to the hip angle. In order to verify the effectiveness of the proposed control, a practical robot with the variant height is constructed, and the proposed control is embedded in the control board. Finally, two experiments are also conducted to verify the balancing and moving ability of the robot with the variant posture

APPLICATION OF MIND MAP IN TEACHING GEOMETRY IN GRADE 4

When it comes to mathematics education and learning, mind maps are a graphical representation of ideas and concepts widely used. A mind map can significantly improve student learning and teacher teaching activities by its unique structure and characteristics. This study demonstrates the feasibility and effectiveness of incorporating a mind map into the geometry curriculum for fourth-grade students. The findings of an experiment conducted on 44 primary students demonstrate that, with the teacher's guidance, most students can create an appropriate mind map to review a lesson and that the mind map contributes to increasing students' learning motivation and subject interests. Several students responded positively to a survey about their attitudes toward using mind maps in mathematics learning, which revealed that they have favorable attitudes toward using mind maps.  Article visualizations

Study change of the performance of airfoil of small wind turbine under low wind speed by CFD simulation

Renewable energy has received strong attention and investment to replace fossil energy sources and reduce greenhouse gas emissions. Quite good and good wind speed areas have been invested in building large-capacity wind farms for many years. The low wind speed region occupies a very large on the world, which has been interested in the exploitation of wind energy in recent years. In this study, the original airfoil of S1010 operated at low wind speed was redesigned to increase the aerodynamic efficiency of the airfoil by using XFLR5 software. After, the new VAST-EPU-S1010 airfoil model was adjusted to the maximum thickness and the maximum thickness position. It was simulated in low wind speed conditions of 4-6 m/s by CFD simulation. The lift coefficient, drag coefficient and $C_{L}$/$C_{D}$ coefficient ratio were evaluated under the effect of the angle of attack and the maximum thickness by using the $k-\epsilon$ model. Simulation results show that the VAST-EPU-S1010 airfoil achieved the greatest aerodynamic efficiency at the angle of attack of 3\,^{\circ}, the maximum thickness of 8\% and the maximum thickness position of 20.32\%. The maximum value of $C_{L}$/$C_{D}$ of the new airfoil at 6 m/s is higher than at the 4 m/s by about 6.25\%.Comment: 19 pages, 21 figure

USING A MULTI-CRITERIA DECISION-MAKING MODEL TO EVALUATE AND SELECT AN E-COMMERCE PLATFORM

The COVID-19 pandemic has led to disruptions in consumers' lifestyles and purchases, as well as businesses' online business models. Online platforms are increasingly used for shopping purposes. To evaluate and choose an e-commerce platform requires using many criteria and decision makers. Therefore, the process of evaluating and selecting an e-commerce platform is viewed as a multi-criteria decision-making problem. The objective of this study is to develop a multi-criteria decision-making model to help consumers evaluating the e-commerce platforms. In the proposed model, the ratings of alternatives and the weights of the criteria are evaluated using the linguistic variable. Simulation examples are used to show the effectiveness of the model in practice.  Keywords: Fuzzy TOPSIS, E-Commerce Platform, Mcdm, Fuzzy Sets

Matrix Completion With Variational Graph Autoencoders: Application in Hyperlocal Air Quality Inference

Inferring air quality from a limited number of observations is an essential task for monitoring and controlling air pollution. Existing inference methods typically use low spatial resolution data collected by fixed monitoring stations and infer the concentration of air pollutants using additional types of data, e.g., meteorological and traffic information. In this work, we focus on street-level air quality inference by utilizing data collected by mobile stations. We formulate air quality inference in this setting as a graph-based matrix completion problem and propose a novel variational model based on graph convolutional autoencoders. Our model captures effectively the spatio-temporal correlation of the measurements and does not depend on the availability of additional information apart from the street-network topology. Experiments on a real air quality dataset, collected with mobile stations, shows that the proposed model outperforms state-of-the-art approaches

SYSTEM THEORY BASED MULTIPLE BEAMFORMING

In this paper, the problem of analysis and design of large-scale multiple beamforming system is considered by system theory approach. We consider the response of system parameters by set of objective functions in a critical condition, which is unable to access measurement data or the data size is large. The reduced-order model is built and the robust solution is found for a multiple beamforming system. The Monte Carlo simulation results show that the proposed multiple beamforming system yields significant performance against over existing methods