VNUHCM Journal of Engineering and Technology http://stdjet.scienceandtechnology.com.vn/index.php/stdjet <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 VNUHCM Journal of 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="https://creativecommons.org/licenses/by/4.0/" 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> Large-Scale Fabrication of Polyethylene Glycol-Poly(Methyl Methacrylate) Blend with Nanosponge-Porous Structure for High Performance Bio-Triboelectric Nanogenerator http://stdjet.scienceandtechnology.com.vn/index.php/stdjet/article/view/1024 <p>In this work, blends of polyethylene glycol (PEG) and poly(methyl methacrylate) (PMMA) with nanosponge-like porous structure are fabricated by a solution phase separation method, subsequently the nanosponge-porous blends are also applied for a high performance triboelectric nanogenerator (TENG). The features of the porous structure are controlled by varying polymer concentrations and PEG/PMMA ratios. A TENG device made of porous PEG-PMMA blend and convex-poly(dimethyl siloxane) (c-PDMS) can generate an instantaneous output power of 3.2 mW. TENG can not only serve as a supply power to light several light emitting diodes (LEDs) on but demonstrate high potential applications as self-powered monitoring healthcare sensors.</p> Yen Linh Nguyen Gia Huy Nguyen Hoang Pham Anh Quoc Nguyen Pham Cao Quan Thu Ha Le Thi Le Thanh Nguyen Tran Van Khai Pham Trung Kien Tien Van Bui ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2022-09-18 2022-09-18 5 3 press press 10.32508/stdjet.v5i3.1024 title description none g Application of blade element theory on horizontal axis wind turbines to research a novel dual rotor wind turbine http://stdjet.scienceandtechnology.com.vn/index.php/stdjet/article/view/1004 <p>This research paper applies the blade element momentum theory on a horizontal axis wind turbine to study a 2-stage wind turbine with an independent rotating shaft, a type of small-scale wind turbine that has never been studied. The article also includes the Prandtl loss in the theory of the blade element momentum method to calculate the wind turbine so that the calculated power and efficiency are close to the actual efficiency instead of the consideration of ideal conditions. These theories have been around for a long time, but their applicability is still very high besides the use of modern computational tools such as computational fluid dynamics. Calculation results in the study are achieved by applying basic theories, then comparing with simulation results from Qblade software, a software that is commonly used in studies to calculate small and large-scale horizontal axis wind turbines and gives an error of less than 10%. This method is to ensure the objectivity and authenticity of the article. The proposed method in this study can be used to calculate various blade profiles of wind turbines. The paper aims to use the CL/CD ratio corresponding to a certain angle of attack as a specific case to optimize the calculation process, giving the problem can be automated.</p> Huy Đăng Lê Bao The Nguyen ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2022-10-11 2022-10-11 5 3 press press 10.32508/stdjet.v5i3.1004 title description none g Effect of marble powder content on compressive strength and water absorption of high-strength concrete http://stdjet.scienceandtechnology.com.vn/index.php/stdjet/article/view/1025 <p>This paper presents the effect of marble powder content on compressive strength and water absorption of high-strength concrete to expand the utilization of such waste in the construction industry and to reduce the Portland cement production which negatively affects the environment. Mixture proportion of reference concrete without marble powder was designed as per TCVN 10306:2014 with a designed compressive strength at least of 60 MPa and slump of 16 ± 2 cm. To evaluate the effect of marble powder content on compressive strength and water absorption of hardened concrete, the Portland cement was replaced by the marble powder at levels of 0, 5, 10, 15, and 20% by mass. Experimental results showed that the marble powder significantly affected the engineering properties of fresh and hardened concretes, in detail: the replacement of Portland cement by the marble powder from 0 to 20% increased the slump of fresh concrete from 16.0 to 20.5 cm, and the void volume of hardened concrete at the age of 28 days from 2.66 to 4.79%, resulting in the reduction of compressive strength by 2.48–18.60% and the increase in water absorption by 1.59–3.79% when comprared with the reference concrete with 0% marble powder. However, the value of compressive strength at the age of 28 days of hardened concrete using 5–20% marble powder reached 60.94–73.01 MPa, ensuring the requirement in terms of compressive strength of high-strength concrete. In conclusion, the utilization of marble powder as the Portland cement replacement in a range from 5–20% was feasible in making high-strength concrete with compressive strength of above 60 MPa.</p> Phương Trinh Bùi Xuân Hoàng Đào Phú Nam Trân Phạm Thị Phương Hà Phùng Xuân Lộc Lưu ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2022-10-13 2022-10-13 5 3 press press 10.32508/stdjet.v5i3.1025 title description none g Investigating the effects of ingredient proportions on the texture of Vietnamese sausage using mixture experiment design http://stdjet.scienceandtechnology.com.vn/index.php/stdjet/article/view/1007 <p>In this study, the effect of different ingredient proportions on the textural and hedonic characteristics of Vietnamese sausage was investigated. Vietnamese sausage is a widely popular traditional food of Vietnam, yet its characteristics are rarely investigated, especially the texture and hedonic properties. Vietnamese sausage’s texture was heavily influenced by three main ingredients: lean meat, lard and starch. In order to study the interactive effects of these three ingredients on texture as well as liking, eight samples with different proportions of these three main ingredients were prepared based on the mixture design approach. The textural characteristics (including hardness, cohesiveness, springiness, chewiness and gumminess) were determined using the texture profile analysis method, while a consumer panel (N = 70) evaluated their texture liking score. Surprisingly, all the texture characteristics were statistically significant difference. However, cohesiveness had a small variance between samples, signalling that this attribute is not important in describing the texture of Vietnamese sausage. To model the effect of ingredients, response surface regression with mixture model was carried out. The results showed that Scheffe’s special cubic model had a good fit for hardness (R2 = 0.946), chewiness (R2 = 0.902) while Scheffe’s quadratic model had a good fit for liking score (R2 = 0.967). The lean meat was found to be the ingredient with the largest effect on increasing the textural charactertistics as well as the liking score. Interestingly, upon inspecting the correlation between texture and liking score, the PCA map of both showed a similar structure. Finally, optimal values of the main ingredients for Vietnamese sausage formulations based on hedonic (&gt; 6.5 liking score) were 4% - 8% starch, 70% - 76% lean meat and 18% - 26% lard. The analysis of consumers’ liking scores suggested that springiness is the main driver of liking for Vietnamese sausage products.</p> Hien Thi Nguyen Thinh Huu Pham Dzung Hoang Nguyen ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2022-08-29 2022-08-29 5 3 press press 10.32508/stdjet.v5i2.1007 title description none g Determination of the efficiency of AgNPs/ZIF-8 coating on different substrates http://stdjet.scienceandtechnology.com.vn/index.php/stdjet/article/view/969 <p>Depending on different applications or materials that integrate with the substrate as well as the transduction method used in the biosensors, different materials of the substrate are considered. This research focuses on selecting the appropriate substrate in designing biosensors, detecting microorganisms in the environment. In this study, the glass slide (glass), Polyethylen plastic (PE plastic), and the cellulose paper (cellulose acetate (CA) &amp; cellulose nitrate (CN)) are investigated substrates for coating AgNPs/ZIF-8 – material used as an optical signal amplification in further steps, using structural analysis techniques – Scanning Electron Microscopy (SEM) for morphology characterization and the Energy Dispersive Spectrometer (EDS) for optical characterization. A morphology characterization with SEM showed that cellulose paper is a better substrate in comparing with the other substrates (glass, PE), because the sensity of distribution on CN was the highest (85-90%) when it coated with AgNPs/ZIF-8. According to EDS analysis, the ratios of Ag in mixture on CN substrate (15.38±0.39% mass) is slightly higher than CA substrate (13.58±0.39% mass); and about 53 times higher than glass substrate (0.37±0.13% mass) and PE plastic substrate (0.29±0.08%). Therefore, cellulose paper (CA) will be suggested to select for further research as a new material with cost (inexpensive) and effectiveness in coating AgNPs/ZIF-8.</p> Huyen Thi Bich Trinh Lai Duy Phuong Pham Tan Thi Dang Vu Bich Hanh ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2022-09-30 2022-09-30 5 3 1577 1585 10.32508/stdjet.v5i3.969 title description none g Influence of the louver angle on the performance of the air-conditioning outdoor units in high-rise apartment buildings http://stdjet.scienceandtechnology.com.vn/index.php/stdjet/article/view/970 <p>The split-type air conditioners are widely used in high-rise apartment buildings in the major urban areas, especially Ho Chi Minh City - Vietnam, because of its convenience. In the apartments with limited space, the installation of outdoor units not in accordance with technical guidelines will affect the performance of the air conditioning system and the aesthetics of the apartment building. The aim of this study is to propose the technical room in apartments for properly installing outdoor units of air conditioning systems. The CFD method is utilized through Ansys Fluent software to determine the inlet air temperature of condensers and COP corresponding to the louver angle of 0o, 10o, 20o, 30o và 40o. The results obtained from the simulations show that increasing the louver angle results in rising the inlet air temperature of condensers and reducing COP. The average temperature of the air which entering the condensers does not change significantly when the louver angle increases from 0o to 30o. When the louver angle is more than 30o, the inlet air temperature of outdoor units exceeds the continuous operating temperature of 48oC. To maintain the high performance of the air conditioner during operation, the louver angle is adjusted as small as possible and limited to a value of about 30o.</p> Van Hap Nguyen Minh Phú Nguyễn ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2022-09-30 2022-09-30 5 3 1586 1595 10.32508/stdjet.v5i3.970 title description none g Study of correlation between ink trapping and color difference in overprint http://stdjet.scienceandtechnology.com.vn/index.php/stdjet/article/view/994 <p>The ink trapping value is one of the important parameters affecting the appearance of secondary colors in overprint. Usually, the ink trapping parameter is traditionally calculated based on the solid density values of the primary colors and the overprint color. These density values are measured by the complementary color filter of the color final ink layer, and these ink trapping values can be calculated using the Preucil, Ritz, or Brunner formulas. Furthermore, the density measurement is more suitable for testing the color printing and not for overlapping assessment because these density values are measured by the complementary color filter of the second color ink. The ink has a specific transmittance, and light is not only absorbed but also scattered inside the ink layer, so the total density of the overlapping colors will be less accurate. As a result, the color measurement method is used to describe the effect of ink trapping of the second ink layer on the first layer of ink. The main idea is to use the color difference value to evaluate the ink trapping ability. In this paper, the author has quantitatively analyzed the correlation between the percentage value of ink trapping and the color difference parameter ΔEab*. The studied results show that the ΔEab* value has a linear correlation with the ink trapping value calculated according to the traditional methods based on density values. This result is also aimed at the fluctuant tolerance of ink trapping ratio during four-color printing to achieve the standard color value quickly.</p> Nguyen Thanh Phuong ##submission.copyrightStatement## http://creativecommons.org/licenses/by/4.0 2022-09-30 2022-09-30 5 3 1596 1604 10.32508/stdjet.v5i3.994 title description none g