Science & Technology Development Journal - Engineering and Technology <p><span id="result_box" class="" lang="en"><span title="Tạp chí Phát triển Khoa học và Công nghệ (PTKH&amp;CN) của Đại học Quốc gia thành phố Hồ Chí Minh (ĐHQG-HCM) được thành lập từ năm 1997, ra số đầu tiên vào tháng 1 năm 1998. Từ năm 2006 Tạp chí đã"><strong>Science and Technology Development Journal</strong> (STDJ), Vietnam National University - Ho Chi Minh City (VNU-HCM) was established in 1997. And the first issue was published in January 1998 with </span><span title="đăng ký mã số chuẩn quốc tế ISSN 1859-0128.">ISSN 1859-0128. </span><span title="Từ đó cho đến nay, Tạp chí PTKH&amp;CN đã trở thành diễn đàn khoa học quan trọng nhất của đội ngũ cán bộ nghiên cứu, giảng viên, nghiên cứu sinh của ĐHQG-HCM và cũng là diễn đàn khoa học công nghệ đáng tin cậy của">Since then, STDJ has become the most important scientific forum of scientists from VNU-HCM as well as</span><span title="nhiều nhà nghiên cứu, giảng viên các trường đại học khác tại Việt Nam."> other universities. </span><span title="Tạp chí đã trải qua 20 năm phát triển và đã trở thành nhịp cầu giao lưu khoa học, cũng như làm phong phú tài liệu tham khảo cho đội ngũ giảng viên, nghiên cứu sinh, sinh viên ĐHQG-HCM nói riêng và các Trường đại">The magazine has undergone 20 years of development and has become a bridge for scientific exchanges, as well as enriching reference materials for the faculty, doctoral students, students of VNU-HCM in particular and other universities, institutes... </span></span></p> <p><span id="result_box" class="" lang="en"><span title="học phía Nam nói chung. "><br></span><span title="Tính đến hết năm 2016 Tạp chí đã xuất bản được 276 số với 2714 bài nghiên cứu của các nhà khoa học, cán bộ trong và ngoài ĐHQG-HCM trong 5 lĩnh vực nghiên cứu: Kỹ thuật và Công nghệ, Khoa học Tự nhiên,">By the end of 2016, the journal has published 276 issues with 2714 research articles in five areas of research: Engineering and Technology, Natural Sciences, </span><span title="Khoa học Xã hội và Nhân văn, Kinh tế luật và Khoa học Quản lý, Khoa học Trái đất và Môi trường tương ứng với 5 chuyên san chuyên ngành của Tạp chí.">Social Sciences and Humanities, Economics of Law and Management Sciences, Earth Sciences and Environment corresponding to 5 specialized journals of the Journal. </span></span></p> <p><span id="result_box" class="" lang="en"><span title="Tạp chí đã được phát hành tại các thư viện của các đơn vị thành viên của ĐHQG-HCM, các Sở Khoa học Công nghệ của các tỉnh thành trên cả nước và được Hội đồng học hàm Giáo sư Nhà nước đánh giá cao.">The magazine has been widely indexed in the various libraries at Vietnam. </span></span></p> Viet Nam National University Ho Chi Minh City en-US Science & Technology Development Journal - Engineering and Technology 2615-9872 <p>Copyright The Author(s) 2018. This article is published with open access by Vietnam National University, Ho Chi Minh city, Vietnam. This article is distributed under the terms of the&nbsp;<a href="" target="_blank" rel="noopener">Creative Commons Attribution License (CC-BY 4.0)</a> which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.&nbsp;</p> Optimal location and impacts of 1 MWP solar pv plants on distribution network protection <p>Nowadays, the penetration of the distributed energy resources into the power distribution network is increasing, especially the 1 MWp solar PV plants since they have been enjoying the Feed-in tariff scheme. In order to reduce the losses of the distribution power network efficiently, this paper uses the Symbiotic Organism Search (SOS) algorithm to determine the optimal location for these solar power sources. However, when these distributed power sources are connected to the distribution network, they can cause to lose the selective coordination between reclosers and fuses - the main protection devices of the distribution network. The prominent feature of this report is to be based on the availability of reclosers, fuses, and with consideration of the Khc coefficient (which is affected by the time and number of reclose attempts). Hence, a simple but efficient solution is proposed to ensure selective recloser – fuse coordination. The mentioned SOS algorithm and the solution are to be applied to the 473TH 22 kV distribution network in Tay Ninh province. The simulation results using Matlab and Etap indicate that the SOS algorithm along with the proposed solution are beneficial to planning and locating distributed power sources, and simultaneously help to overcome the non-selective recloser – fuse coordination.</p> Khanh Tuan Dang Tran Huy Hoan Truong Hoang Bao Huy ##submission.copyrightStatement## 2021-08-26 2021-08-26 4 3 1036 1047 10.32508/stdjet.v4i3.815 title description none g Shaping the tooth profile of elliptical gear with the involute ellipse curve <p>Non-circular gears (NCGs) with the advantage of compactness and simple mechanical structure in creating transmitters with variable gear ratios in the industry, so this is a topic that is being studied by many scientists. However, up to now the research usually focuses on NCGs with tooth profile that is an involute circle called involute tooth profile, while other curves have not been applied in the design of the non-circular gears. In this paper, the author proposes to apply the involute ellipse curve in shaping the tooth profile of the pair of elliptical gears with a rack cutter. A rack cutter with tooth profiles is trapezoidal weight is determined from the involute ellipse curve selected as the NCGs teeth. In order not to undercut and tip sharpening when shaping the gear, two algorithms for correcting the base ellipse according to the even distribution of teeth on the gear and undercutting avoidance condition are performed. A numerical computational software module is written according to the theory and the algorithm is implemented to explore the different cases in the design process. The results of this study show that the teeth are evenly distributed over the entire circumference of the ring elliptical gear, overcoming the phenomenon of uneven teeth in geometry and size when using the involute of a circle as other studies have shown. Also, with the tooth profile that is involute ellipse curve, the pressure angle is increased to improve efficiency the transmission capacity of a pair of gears. Therefore, this is the advantage of the new profile in creating variable automatic transmission for different script applications in industries such as the automotive industry or modern medical equipment.</p> Thai Hong Nguyen ##submission.copyrightStatement## 2021-08-30 2021-08-30 4 3 1048 1056 10.32508/stdjet.v4i3.820 title description none g Research on application of industrial robots in automated fueling systems for small individual cars <p>An automated fueling system for small individual vehicles, such as 4- and 7-passenger cars, is necessary in the modern life. Currently in the car market, in terms of the characteristics of the equipped fuel tanks, it can be divided into two main groups, including the vehicles using the traditional fuel tanks and the vehicles using the cap-less fuel tanks. For the vehicles using the traditional fuel tanks, the vehicle drivers need 4 steps to pump the gasoline. They are opening the outer lid of the body, opening the screw cap on the fuel tank, putting the pump nozzle into the fuel tank and making the fuel pump. For the vehicles using the cap-less fuel tank design, the manufacturers replace the traditional screw cap with the self-opening (close) lid mechanism when there is (without) the pump nozzle. So when operating the gasoline pump, there is no step to open the screw cap on the fuel tank. This new design was pioneered by American car manufacturers such as Ford and General Motor. This paper proposes a solution for the automatic fueling for the vehicles that have the fuel tank without the screw cap. The system is built based on an industrial robot that do the task replacing for the station officer. Firstly, a special tool is designed to help the robot to operate during the automatic fueling. Next, an image processing algorithm is applied to recognize the position of the fuel tank of the vehicles. After that, an automatic fueling algorithm is proposed so that the system can do fueling automatically. The proposed solution is verified by the experiments on the real model. The experimental results show that the proposed system can be used to position the nozzle into the fuel tank with the acceptable error</p> Chi Tam Lam Tri Cong Phung ##submission.copyrightStatement## 2021-09-04 2021-09-04 4 3 1057 1067 10.32508/stdjet.v4i3.848 title description none g Research of Applying forecasting theory to establish the optimal load transfer strategy for maintenance at 110kV substation <p>Regarding electric power systems, Short-Term load forecasting plays a pivotal role in the planning and synchronous operation of an electric grid. In recent years, because of the computer industry developing at an ever-accelerating rate, plenty of sophisticated load forecasting models have been better utilized, thereby becoming more and more widely used. However, in VietNam, there is no practical use of these models, and load forecasting is still mainly based on engineers’ personal experiences. Due to the fact that experiences are not absolutely precise, applying conventional load forecasting techniques easily results in many severe consequences. Therefore, in this article, the necessity, as well as benefits of using load forecasting models for the VietNam power grid, will be clearly and thoroughly demonstrated. This paper, additionally, provides a suggested optimal load transfer strategies for 110 kV substations when these substations are under maintenance, avoiding overload for transformers and nearby feeders. Through specific examples and statistics data, the efficiency of methods suggested in this article has been proved.</p> Huỳnh Tiến Đạt Nguyễn Thị Bích Tuyền Lê Thị Tịnh Minh Nguyễn Ngọc Phúc Diễm Lê Quang Bình Lâm Bửu Quí ##submission.copyrightStatement## 2021-09-07 2021-09-07 4 3 first first 10.32508/stdjet.v4i3.826 title description none g Calibrating water distribution network models and identifying interference areas between water sources on the network in the North of Ho Chi Minh City <p>The realistic simulation model of a water distribution network has been widely applied in water resource management, from optimization design to operation management. However, the calibration of the model simulation to adapt with reality is still a challenging task, because within the water distribution network, there are numerous unknown variables, such as: variant consumptions, pipeline characteristics, losses and uncontrollable or non-revenue water, especially flows at potential leak points. This study presents the simulation and calibration of the hydraulic model of the water distribution network in the Northern area of Ho Chi Minh City, including Go Vap District and a part of District 12. The network currently supplies water for more than 140.000 water meters and the water flow into and out of the network in real time is controlled in the study area. The results of the calibration of the water distribution network model are assessed to be consistent with the actual operation in terms of flow and water pressure changes during the day at the observation points by performance metrics. On that basis, the study continues to apply the calibrated model to analyze the water source tracing to determine the interference areas between two water sources in the study area from two water treatment plants.</p> Ho Minh Thong Le Van Duc Nguyen Quoc Phong Nguyen Thi Thanh Duyen ##submission.copyrightStatement## 2021-09-11 2021-09-11 4 3 1068 1078 10.32508/stdjet.v4i3.830 title description none g Design of low cost-remote eye tracker using Pupil Center-Corneal Reflection technique <p>The eye tracker is used in many fields such as education, marketing, psychology, medicine, among others. However, commercial devices are costly, spanning from a few hundred to several thousand dollars. Therefore, an inexpensive-monocular-remote (IMR) eye tracker is developed for education and research, which implements the Pupil-Center-Corneal-Reflection technique. The IMR device consists of a low-cost camera with a near-IR pass filter that captures subject’s eye images, a moderate-cost computer that processes these images, as well as two near-IR light sources that create glints and illuminate the eye. The pupil detection algorithm is developed by combining the advantages of two recent algorithms, named BORE and PDIF, and gaze points are estimated from pupil-glints vectors via a fourth-order polynomial. An experimental evaluation is conducted concurrently on the research eye tracker IMR at the operating frequency of 30 Hz and the commercial-high-end-head-free device VT3 Mini at 60 Hz, in a challenge condition: subjects sit down near a window, and some of them wear glasses. Also, their heads are placed on a fixed chin rest, and the data is acquired when both devices successfully estimate gaze points. The experimental results in 11 sample data, obtained from 7 subjects, show that the overall ratio of the number of filtered/raw samples and raw/idea samples are 88.92% and 98.63% in order. Whereas the overall precision of the IMR eye tracker is nearly equal to that of the VT3 Mini device (0.57 degrees and 0.54 degrees, respectively), the overall accuracy of the proposed eye tracker is better than that of the commercial device (1.04 degrees and 1.34 degrees, respectively). Regarding eye safety, the radiant power and the burn-hazard-weighted radiance of the proposed device are much smaller than their limitations, according to IEC 62471. With these results, the IMR eye tracker is appropriate for education and needs to be improved in terms of data validation to satisfy the research purpose.</p> Phu Tuong Do Linh Quang Huynh Dang Cao Le Tin Trung Tran ##submission.copyrightStatement## 2021-09-11 2021-09-11 4 3 1079 1092 10.32508/stdjet.v4i3.856 title description none g Study of glycerol-methanol and sorbitol-methanol mixed feed strategies for recombinant hPDGF-BB production in Pichia pastoris <p>The recombinant human platelet-derived growth factor type BB (rhPDGF-BB) protein has been approved by FDA for diabetic foot ulcer treatment due to its function of stimulating cell proliferation and wound healing. In this study, the production of rhPDGF-BB from Pichia pastoris is studied in a 7.5 L fermentation using methanol as carbon source and inducer in induction phase. The specific growth rate of the recombinant strain reduced 1.833-fold and rhPDGF-BB productivity reduced 2.13-fold compared to at 0.5 L. To improve growth and protein expression of the strain in induction phase, the mixed feed strategy, in which glycerol or sorbitol was co-fed with methanol at three different molar ratios (1:1, 1:2 and 1:3) was conducted. Using the mixture of glycerol and methanol at the molar ratio 1:2 and the mixture of sorbitol and methanol at the molar ratio 1:3 increased the productivity of rhPDGF-BB protein 1.32-fold (280,48 mg/L) and 1.24-fold (264,15 mg/L), respectively, higher than using only methanol in the induction phase of the fermentation process.</p> Lạc Trần Hà Nghĩa Trung Lê Bảo Lê Hoài Nguyễn Đạt Tiến Ân Vinh Hiền Huỳnh Huy Hoàng Đặng Đông Đình Lê Nhân Trí Nguyễn ##submission.copyrightStatement## 2021-09-13 2021-09-13 4 3 first first 10.32508/stdjet.v4i3.858 title description none g