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A study on the influence of ignition energy on ignition delay time and laminar burning velocity of lean methane/air mixture in a constant volume combustion chamber 定容燃烧室中点火能量对稀甲烷/空气混合气点火延迟时间和层流燃烧速度影响的研究
Journal of Science and Technology Issue on Information and Communications Technology Pub Date : 2021-12-31 DOI: 10.31130/ud-jst2021-009e
Nguyen Minh Tien Nguyen
{"title":"A study on the influence of ignition energy on ignition delay time and laminar burning velocity of lean methane/air mixture in a constant volume combustion chamber","authors":"Nguyen Minh Tien Nguyen","doi":"10.31130/ud-jst2021-009e","DOIUrl":"https://doi.org/10.31130/ud-jst2021-009e","url":null,"abstract":"This study presents the effect of ignition energy (Eig) on ignition delay time (tdelay) and uncertainty of laminar burning velocity (Su0) measurement of lean methane/air mixture in a constant volume combustion chamber. The mixture at an equivalence ratio of 0.6 is ignited using a pair of electrodes at the 2-mm spark gap. Eig is measured by integrating the product of voltage V(t) and current I(t) signals during a discharge period. The in-chamber pressure profiles are analyzed using the pressure-rise method to obtain tdelay and Su0. Su0 approximates 8.0 cm/s. Furthermore, the increasing Eig could shorten tdelay, leading to a faster combustion process. However, when Eig is greater than a critical value, called minimum reliable ignition energy (MRIE), the additional elevating Eig has the marginal effect on tdelay and Su0. The existence of MRIE supports to optimize the ignition systems and partly explains why extreme-high Eig>> MRIE has less contribution to engine performance.","PeriodicalId":262140,"journal":{"name":"Journal of Science and Technology Issue on Information and Communications Technology","volume":"50 4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123399266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
An optimal algorithm for convex minimization problems with nonconstant step-sizes 非常步长凸极小化问题的最优算法
Journal of Science and Technology Issue on Information and Communications Technology Pub Date : 2021-12-31 DOI: 10.31130/ud-jst2021-012e
Pham Quy Muoi Pham
{"title":"An optimal algorithm for convex minimization problems with nonconstant step-sizes","authors":"Pham Quy Muoi Pham","doi":"10.31130/ud-jst2021-012e","DOIUrl":"https://doi.org/10.31130/ud-jst2021-012e","url":null,"abstract":"In [1], Nesterov has introduced an optimal algorithm with constant step-size,  with  is the Lipschitz constant of objective function. The algorithm is proved to converge with optimal rate . In this paper, we propose a new algorithm, which is allowed nonconstant step-sizes . We prove the convergence and convergence rate of the new algorithm. It is proved to have the convergence rate  as the original one. The advance of our algorithm is that it is allowed nonconstant step-sizes and give us more free choices of step-sizes, which convergence rate is still optimal. This is a generalization of Nesterov's algorithm. We have applied the new algorithm to solve the problem of finding an approximate solution to the integral equation.","PeriodicalId":262140,"journal":{"name":"Journal of Science and Technology Issue on Information and Communications Technology","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121664209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Enhanced removal of phosphate from wastewater by precipitation coupled with flocculation 沉淀-絮凝法强化废水中磷酸盐的去除
Journal of Science and Technology Issue on Information and Communications Technology Pub Date : 2021-12-31 DOI: 10.31130/ud-jst2021-010e
H. Ho
{"title":"Enhanced removal of phosphate from wastewater by precipitation coupled with flocculation","authors":"H. Ho","doi":"10.31130/ud-jst2021-010e","DOIUrl":"https://doi.org/10.31130/ud-jst2021-010e","url":null,"abstract":"Eco-friendly flocculants of alginic acid, NaHCO3 and CaCl2.2H2O with advantages of strong gelation characteristics were prepared for supporting the removal of phosphate in synthetic wastewater using CaO and Ca(OH)2 as precipitants. The effects of weight ratios of each component in flocculants, dosage of flocculants and initial phosphate concentration were investigated through batch of experiments. The results showed excellent flocculation performance with the weight ratio of alginic acid:NaHCO3 and CaCl2.2H2O at 1:0.3:0.02 and the dosage of flocculants at 0.0050 g/25 mL of phosphate solution in the range of initial phosphate concentration from 50 to 1000 ppm. Comparing to the sample without flocculants, the phosphate removal efficiency using CaO and Ca(OH)2 with the addition of flocculants increased from 19 and 20% to 97% at the initial phosphate concentration of 50 ppm, respectively by filtration of filter paper 2.7 μm.","PeriodicalId":262140,"journal":{"name":"Journal of Science and Technology Issue on Information and Communications Technology","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122994416","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
Ownership complexity and loan quality: Evidence for listed commercial banks in Vietnam 所有权复杂性与贷款质量:越南上市商业银行的证据
Journal of Science and Technology Issue on Information and Communications Technology Pub Date : 2021-12-31 DOI: 10.31130/ud-jst2021-018e
Phan Hoang Long Phan
{"title":"Ownership complexity and loan quality: Evidence for listed commercial banks in Vietnam","authors":"Phan Hoang Long Phan","doi":"10.31130/ud-jst2021-018e","DOIUrl":"https://doi.org/10.31130/ud-jst2021-018e","url":null,"abstract":"This paper examines the relationship among aspects of bank ownership complexity, including ownership dispersion and type, and the quality of bank loan portfolio. The data used for analysis is an unbalanced panel consisting of 13 listed commercial banks in Vietnam for the period of 2010 - 2019. The non-performing loan (NPL) ratio is used as an indicator of loan quality. The results showed that ownership dispersion, calculation based on the Herfindahl–Hirschman Index of large shareholding, improves the loan quality. Foreign ownership is also found to have positive impact on the loan quality. However, there is no relationship established between government ownership and loan quality.","PeriodicalId":262140,"journal":{"name":"Journal of Science and Technology Issue on Information and Communications Technology","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123470723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
An investigation on verbal bullying among Danang high school students 岘港高中学生言语欺凌调查
Journal of Science and Technology Issue on Information and Communications Technology Pub Date : 2021-06-30 DOI: 10.31130/jst-ud2021-443
L. Le
{"title":"An investigation on verbal bullying among Danang high school students","authors":"L. Le","doi":"10.31130/jst-ud2021-443","DOIUrl":"https://doi.org/10.31130/jst-ud2021-443","url":null,"abstract":"Bullying among students in general and high school students in particular has become a pressing issue in the world and in Vietnam today. The paper focuses on investigating verbal bullying between high school students in Da Nang city, and developing measures to reduce bullying in high school students. Methods used in the research include theoretical analysis and synthesis, questionnaire, in-depth interviews, and educational experiment. Verbal bullying is explored in terms of the level and content of bullying, the awareness of consequences of bullying on students. Mitigating measures of verbal bullying are designed to use peer-to-peer influences through behavioral club activity, social networking forums, and acting in bullying situations brochure-building activities. The interventions are designed to focus on enhancing the ability to control emotions and form appropriate behaviors, thereby reducing verbal bullying. Experimental measures are implemented through real-life activities undertaken by high school students. Research findings reveal that all the measures suggested in the research appeared effective. Peer education is an effective option to influence verbal bullying behavior in high school students.","PeriodicalId":262140,"journal":{"name":"Journal of Science and Technology Issue on Information and Communications Technology","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130373195","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
An investigation into morphological and semantic features of conversion words denoting human body parts in English and Vietnamese business news 英语和越南语商业新闻中表示人体部位的转换词的形态和语义特征研究
Journal of Science and Technology Issue on Information and Communications Technology Pub Date : 2021-06-30 DOI: 10.31130/jst-ud2021-448
Le Kim Tien, Nguyen Huu Quy Le
{"title":"An investigation into morphological and semantic features of conversion words denoting human body parts in English and Vietnamese business news","authors":"Le Kim Tien, Nguyen Huu Quy Le","doi":"10.31130/jst-ud2021-448","DOIUrl":"https://doi.org/10.31130/jst-ud2021-448","url":null,"abstract":"In this research, the author has applied descriptive along with contrastive analysis methods to investigate morphological and semantic features and pointed out the morphological and semantic differences of conversion words denoting human body parts in English and Vietnamese business news. Specifically, the online newspapers are Vietnam news, CNN, VnEconomy and Vnexpress; the author also used qualitative approach to collect the data. This study aims to examine two linguistic features as well as explore the differences of  features of conversion words denoting human body parts in English and Vietnamese business news based on the contrastive analysis of 50 English and 50 Vietnamese conversion words. The article proposes the particular identification and meanings of conversion words denoting human body parts in English and Vietnamese business news so that it helps Vietnamese learners and translators efficiently use conversion words in learning as well as translating.","PeriodicalId":262140,"journal":{"name":"Journal of Science and Technology Issue on Information and Communications Technology","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134144828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
An investigation into copper-binding capacity of the white leg shrimp head (Litopenaeus vannamei) protein hydrolysate 凡纳滨对虾(Litopenaeus vannamei)白腿虾头蛋白水解物铜结合能力的研究
Journal of Science and Technology Issue on Information and Communications Technology Pub Date : 2020-12-31 DOI: 10.31130/JST-UD2020-154E
T. Vo
{"title":"An investigation into copper-binding capacity of the white leg shrimp head (Litopenaeus vannamei) protein hydrolysate","authors":"T. Vo","doi":"10.31130/JST-UD2020-154E","DOIUrl":"https://doi.org/10.31130/JST-UD2020-154E","url":null,"abstract":"The aim of this study is to obtain the copper-binding protein hydrolysate from the white leg shrimp head (WLSH) by-product using enzymatic hydrolysis. The outcome indicated that the copper-binding capacity (CBC) of the WLSH protein hydrolysate achieved the maximum value of 19.4±0.5 mg Cu2+/g protein with hydrolysis conditions including Flavourzyme preparation, pH 7.5, 50°C, the enzyme:substrate (E:S) ratio of 80 U/g protein and 5h of hydrolysis. Under the pH treatment in a range of 1-11 or heat treatment at 100°C for up to 180 min, its CBC remained over 80%. The water holding capacity (WHC) and the oil-holding capacity (OHC) of the protein hydrolysate were 4.1±0.1 ml water/g protein hydrolysate powder and 4.5±0.1 ml oil/g protein hydrolysate powder, respectively. The solution also encompassed up to 8 essential amino acids, accounting for 36.1% of the total amino acid content. The protein hydrolysate could serve not only as a copper chelating agent, preventing copper-deficient or superfluous relating diseases, but also as a texturizer and an amino acid supplement fortified in various types of food.","PeriodicalId":262140,"journal":{"name":"Journal of Science and Technology Issue on Information and Communications Technology","volume":"160 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127405337","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
An improved iris recognition system based on the fusion of the curvelet and DTCWT 基于曲线波与DTCWT融合的改进虹膜识别系统
Journal of Science and Technology Issue on Information and Communications Technology Pub Date : 2020-12-31 DOI: 10.31130/JST-UD2020-135E
Nguyen Nam Phuc, Lê Tiến Hưng, N. Q. Trung, Ha Huu Huy Nguyen
{"title":"An improved iris recognition system based on the fusion of the curvelet and DTCWT","authors":"Nguyen Nam Phuc, Lê Tiến Hưng, N. Q. Trung, Ha Huu Huy Nguyen","doi":"10.31130/JST-UD2020-135E","DOIUrl":"https://doi.org/10.31130/JST-UD2020-135E","url":null,"abstract":"In recent years, iris recognition has been emerged as one of the most popular biometric techniques because it guarantees high universality, distinctiveness, permanence, collectability, performance, acceptability, circumvention. In the paper we propose an improved system for iris recognition with high accuracy by fusing curvelet and dual tree complex wavelet transform. In our system, the main features are extracted from pre-processed/normalized iris images using both curvelet and Dual Tree Complex Wavelet Transform (DTCWT) tranforms. After performing different classifiers independently, all the results are fused to get final classification in the decision level to increase the accuracy of system. Finally, the random forest classifier and CATIA dataset are used to measure the performance of the proposed method. The experimental results show that the technique of the paper based on fusion of the curvelet and DTCWT is promising when compared with other existing similar techniques.","PeriodicalId":262140,"journal":{"name":"Journal of Science and Technology Issue on Information and Communications Technology","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125817703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Stability analysis of an isolated microgrid with the presence of the hybrid energy storage system-based virtual synchronous generator 基于混合储能系统的虚拟同步发电机的隔离微电网稳定性分析
Journal of Science and Technology Issue on Information and Communications Technology Pub Date : 2020-06-30 DOI: 10.31130/JST-UD2020-101E
V. T. Nguyen, Thanh Nguyen
{"title":"Stability analysis of an isolated microgrid with the presence of the hybrid energy storage system-based virtual synchronous generator","authors":"V. T. Nguyen, Thanh Nguyen","doi":"10.31130/JST-UD2020-101E","DOIUrl":"https://doi.org/10.31130/JST-UD2020-101E","url":null,"abstract":"Nowadays, isolated microgrids formed by distributed generators based on renewable energy sources and power electronic converters have become more and more popular. There has been a lot of research for improving the stability of microgrids in recent years particularly the virtual synchronous generator (VSG) is a topic of great interest. This paper presents the stability analysis of an isolated microgrid based on wind-photovoltaic-diesel hybrid energy sources with the introduction of a proposed VSG. The proposed VSG is based on a battery-supercapacitor (SC) hybrid energy storage system aiming to maintain the stability of the studied isolated microgrid under disturbance conditions. The time-domain simulation results of the studied system under various disturbance conditions are examined to evaluate the effectiveness of the proposed VSG. It can be concluded from the simulation results that the proposed VSG can effectively compensate power fluctuations and maintain the stability of the studied microgrid under various disturbance conditions. The simulation results also show that while the battery can handle the long-term power variations, the SC can absorb the rapid power fluctuations. Thus, the proposed VSG based on a combination of the battery and the SC could improve the battery’s lifetime and reduce the invested cost of the SC.","PeriodicalId":262140,"journal":{"name":"Journal of Science and Technology Issue on Information and Communications Technology","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115101755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 2
Development of restaurant serving robot using line following approach 基于线路跟踪方法的餐厅服务机器人的开发
Journal of Science and Technology Issue on Information and Communications Technology Pub Date : 2019-12-31 DOI: 10.31130/jst-ud2019-087
Thanh Vo Nhu
{"title":"Development of restaurant serving robot using line following approach","authors":"Thanh Vo Nhu","doi":"10.31130/jst-ud2019-087","DOIUrl":"https://doi.org/10.31130/jst-ud2019-087","url":null,"abstract":"As the era of industrial revolution 4.0 is coming, most of robots are developed to replace the human works and services. However, in Vietnam, putting robots in service industry such as waiter robot serving in restaurants is still very limited. This study presents the initial development of restaurant serving robot using line following approach. The robot is designed by referring to the survey on the size and appearance requirements at a restaurant. Robot is programmed to come to a specific table by mapping data. Based on the line reading algorithm implemented on microcontroller PIC18F4550, the robot follows the line marked on the floor to move to the desired table position and returns to the service counter after completing the task. There are ultrasonic sensors on the robot that can detect the obstacle to help the robot stop and output warning signal. The robot also can output some simple voices to customers in English, Korean and Vietnamese such as \"Welcome\", “Please enjoy your food\"...","PeriodicalId":262140,"journal":{"name":"Journal of Science and Technology Issue on Information and Communications Technology","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124721217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
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