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Can Tho University Journal of Science (CTUJS) is an international double-blind peer-reviewed journal that publishes high quality original research and review articles in multi-disciplines covering natural sciences, technology, environment, agriculture, fisheries, biotechnology, social sciences, humanities, education, economics, law, etc... Read more

Build coconut counting system using image technology

Nguyen Huu Quang, Truong Quoc Bao*, Ngo Quang Hieu
Abstract | PDF
In our country today, the counting of dried coconuts at the production facilities is done manually, takes a lot of time and is not accurate. The goal of this study is to build an automatic, fast and accurate coconut counting system. The study was conducted on the peeled dried coconut fruit with a diameter of 15 cm to 20 cm using image processing technology and open-source computer vision library - OpenCV library. The algorithm includes four main steps. First, determine the object and the background using the Otsu segmentation method. Next, estimate the distance between the background and the object to determine the closest area to the center of the object. Then, find the contour, determine the center and area of the object to reduce the noise. The watershed segmentation algorithm is used to separate overlapping and stacking objects. Finally, count the number of objects contained in the image. In the initial experimental results, the counting system has had an accuracy of over 95% with processing time per image about 75 ms and the counting capacity of the system is over 2000 fruits/hour has confirmed the efficiency of the proposed method.

Application of different control algorithms on a ‘home-made’ temperature control lab kit

Nguyen Nhu Tuong An, Do Vinh Quang*, Pham The Thinh, Tran Nguyen Tuan
Abstract | PDF
Providing enough facilities for students to do laboratory activities is important. An existing useful kit was proposed for students learning a variety of control engineering topics. A temperature control lab kit is made from scratch using common electronics components as a replacement for the original TCLab introduced by Hedengren (Hedengren et al., 2019). Mathematical models of the system derived from theoretical and experimental methods are simulated in Matlab/Simulink to verify their accuracy to the physical kit. Different control algorithms such as: On/Off, PID, Fuzzy are then applied on the Kit as well as its mathematical models to illustrate their control feasibility. Human machine interface (HMI) is also designed using Matlab GUI allowing an operator to select a control algorithm, tune control parameters and monitor parameters of the process. Experimental results show that the derived models can reflect quite well dynamics of the physical kit with temperature deviation among them in the range of ±3°C.  This confirms that the kit is well-suited for teaching different control topics such as system modelling, system identification, classical control and advanced control algorithms.

Fabrication of PZT Thick Film by Electrophoretic Deposition on the Platinum Substrate

Ngo Truong Ngoc Mai*, Iasmi Sterianou, Ian Reaney, Luong Huynh Vu Thanh, Cao Luu Ngoc Hanh, Dang Huynh Giao
Abstract | PDF
PbZrxTi1-xO3 compositions near morphotropic phase boundary have been reported to have high piezoelectric properties. In this study, Pb(Zr0.5Ti0.5)O3 (PZT 50/50) powder was produced by the solid-state reaction from the relevant oxides at 950oC. Phase analysis using X-ray diffraction revealed the single phase of the tetragonal perovskite structure. PZT thick film was fabricated by electrophoretic deposition of the resulted PZT powder onto the Pt substrate. The electrophoretic deposition process was conducted in an ethanol medium, and the effects of deposition parameters such as pH, applied voltage and deposition time on the film thickness were investigated. A green film with a maximum thickness of ~95 μm and sintered film with a maximum thickness of 80±2 μm were prepared. The effects of sintering atmosphere and temperatures on phase transformation and microstructures of PZT film were evaluated using X-ray diffraction and scanning electron microscopy. At room temperature, a PZT film of 68 ± 2 μm thickness has a relative permittivity of 477 ± 13 and ~ 9,500 at TC = 405oC, showing typical dielectric properties.

Attitudes towards cycling in Long Xuyen, Viet Nam: An exploratory study

Vo Thi Hong Nhung*
Abstract | PDF
The promotion of cycling has recently received strong support from the Vietnamese government, and there has been a call for changes in planning to create suitable environment for cycling. However, knowledge in this field is limited since the travel behavior literature in Viet Nam focused on other travel modes, and the context of small cities was largely ignored. The aim of this research is to understand people’s attitudes towards cycling in a small city like Long Xuyen. This serves as an exploratory study to inform and develop future research on this issue. A qualitative approach was used to identify the main influences affecting people’s cycling decisions. The results showed that people’s cycling choice was affected by attitudinal factors, subjective norms, and perceived behavioral control. Interestingly, habit was also found to impact people’s choice of cycling.

Analyzing the factors affecting the high school dropout in Ca Mau

Nguyen Dinh Thanh, Nguyen Thanh Hai, Pham Thi Ngoc Diem*
Abstract | PDF
The yearly dropout rate of high school students of Ca Mau was relatively high (as of 5.61% in the school year 2019–2020). The problems and consequences of dropping out of school might raise numerous social problems. Therefore, this study is to examine the factors affecting the students’ dropout of high school in Ca Mau province and propose several solutions to reduce the dropout rate. Data were collected from 06 districts in Ca Mau in 2019–2020 by interviewing 268 parents and 16 educational managers and surveying 168 homeroom teachers in high schools. The analysis results demonstrate that the main reasons for students’ dropout were poor academic performance (57.46%), economic difficulties (26.87%), living in an unhappy family (9.33%), and improper learning motivation (6.34%). The findings provided crucial information for practically efficient solutions in reducing the high school dropout rate in Ca Mau.

Physicochemical, antioxidant and microbiological behavior of soursop purees during thermal treatment

Hoang Quang Binh, Duong Thi Ngoc Diep*, Ho Thi Thuy Linh
Abstract | PDF
In this study, the influence of thermal treatment at temperatures 70, 80, and 90°C for 0 to 45 minutes on the quality of soursop puree was investigated in terms of physicochemical properties and antioxidant activity. Total phenolic content and antioxidant activity of the sample were evaluated using spectrophotometric methods, ascorbic acid was tested using the titration method.  The result showed that high temperature and prolonged heat treatment accelerated the degradation of physicochemical properties in soursop puree. The kinetic degradation of polyphenol, ascorbic acid, and antioxidant activity belonging to temperature was performed by Arrhenius equation with the Ea values were 54.42 kJ/mol, 48.83 kJ/mol, and 20.07 kJ/mol, respectively. Total aerobic counts and ∆E values of all samples were less than 1 x 102 CFU/g and 2.51, respectively. The soursop puree reached a good quality for all the tested attributes at 80°C for 15 minutes.

Impact of temperature and relative humidity on physicochemical properties of the spray dried red flesh pitaya powder during storage

Duong Thi Ngoc Diep*, Nguyen Hong Ngoan, Hoang Quang Binh
Abstract | PDF
This study was carried out to evaluate the changes in physicochemical properties of pitaya powder produced by spray-drying under the different temperature storage at 5-7 , room temperature, and 50  for 40 days, The results showed that delta E of color increased but the content of betacyanin and total phenolic decreased following temperature increase. The degradation of betacyanin and total phenolic content in all samples during storage fitted the first-order reaction. Moreover, the behavior of moisture content in pitaya powder under different relative humidity was investigated. The isotherm curve of pitaya powder was built (y = 3,2655e0,0106x). The result also showed the GAB equation can be used to calculate the M0 of the sample better than the BET equation. 

An object detection method for aerial hazy images

Tran Tuan Minh *, Tran Van Bao, Vo Duy Nguyen, Nguyen Tan Tran Minh Khang
Abstract | PDF
Image processing and object detection in aerial images have to deal with a lot of trouble due to the existence of haze, smoke, dust in the atmosphere. These factors can blur objects and severely decline image quality which might lead to incorrect or missing object detection. To solve this problem, this study shows a method that can reduce the bad effect of haze on object detection in aerial images. A combination of a dehazing method called Feature Fusion Attention Network (FFA-Net) and an object detection method named Probabilistic Anchor Assignment (PAA) was conducted to evaluate two hypotheses: (1) haze was a noisy factor and (2) haze was treated as part of objects. Through extensive experiments, the selective dehazing hypothesis, which was used for truck objects, improved the detection result of car and bus from 19.6% to 21.9% and 0.7% to 4.4%, respectively, on the UAVDT-Benchmark-M dataset. This result showed that our approach was effective.