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Line Impedance Estimation Based Adaptive Droop Control Method for Parallel Inverters
Le, Phuong Minh,Pham, Xuan Hoa Thi,Nguyen, Huy Minh,Hoang, Duc Duy Vo,Nguyen, Tuyen Dinh,Vo, Dieu Ngoc The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.1
This paper presents a new load sharing control for use between paralleled three-phase inverters in an islanded microgrid based on the online line impedance estimation by the use of a Kalman filter. In this study, the mismatch of power sharing when the line impedance changes due to temperature, frequency, significant differences in line parameters and the requirements of the Plug-and-Play mode for inverters connected to a microgrid has been solved. In addition, this paper also presents a new droop control method working with the line impedance that is different from the traditional droop algorithm when the line impedance is assumed to be pure resistance or pure inductance. In this paper, the line impedance estimation for parallel inverters uses the minimum square method combined with a Kalman filter. In addition, the secondary control loops are designed to restore the voltage amplitude and frequency of a microgrid by using a combined nominal value SOGI-PLL with a generalized integral block and phase lock loop to monitor the exact voltage magnitude and frequency phase at the PCC. A control model has been simulated in Matlab/Simulink with three voltage source inverters connected in parallel for different ratios of power sharing. The simulation results demonstrate the accuracy of the proposed control method.
Line Impedance Estimation Based Adaptive Droop Control Method for Parallel Inverters
Phuong Minh Le,Xuan Hoa Thi Pham,Huy Minh Nguyen,Duc Duy Vo Hoang,Tuyen Dinh Nguyen,Dieu Ngoc Vo 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.1
This paper presents a new load sharing control for use between paralleled three-phase inverters in an islanded microgrid based on the online line impedance estimation by the use of a Kalman filter. In this study, the mismatch of power sharing when the line impedance changes due to temperature, frequency, significant differences in line parameters and the requirements of the Plug-and-Play mode for inverters connected to a microgrid has been solved. In addition, this paper also presents a new droop control method working with the line impedance that is different from the traditional droop algorithm when the line impedance is assumed to be pure resistance or pure inductance. In this paper, the line impedance estimation for parallel inverters uses the minimum square method combined with a Kalman filter. In addition, the secondary control loops are designed to restore the voltage amplitude and frequency of a microgrid by using a combined nominal value SOGI-PLL with a generalized integral block and phase lock loop to monitor the exact voltage magnitude and frequency phase at the PCC. A control model has been simulated in Matlab/Simulink with three voltage source inverters connected in parallel for different ratios of power sharing. The simulation results demonstrate the accuracy of the proposed control method.
Factors Influencing on Consumer's Decision on Vegetarian Diets in Vietnam
NGO, Vu Quynh Thi,VO, Thi Anh Dao,NGO, Anh Phung,NGUYEN, Do Mai Anh,LE, Minh Thu,TO, Thi Phuong Loan,NGUYEN, Thi Thuy Phi Korea Distribution Science Association 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.2
Recently, vegetarian diets have experienced a dramatic increase in popularity. The aim of the study is to explore and test the relationship between the factors influencing consumers' dietary decisions in Ho Chi Minh City, Vietnam. The questionnaire applied a five-point Likert scale to investigate factors that affect Ho Chi Minh City's citizens when they have a vegetarian diet. 497 respondents (68% female; 61.2% aged 18-22; 82.7% had regular vegetarian diets) living in Ho Chi Minh City took part in both online and offline surveys. The results were processed by SPSS 22.0 software. The reliability was checked by Cronbach Alpha and Exploratory factor analysis (EFA) to identify the underlying relationships between measured variables. The Correlation analysis was implemented to show how strong and degree of two variables are related to each other before the multivariate regression equation was analyzed. The result showed the Five factors that were motivating people in Ho Chi Minh City to decide on plant-based diets, such as Animal Welfare, Health, Religion, Mood, and Reference groups. The mood is the most influential variable that significantly influences people's food choices. Attitudes toward vegetarian diets are changing. Therefore, recognizing the trends in food consumption might help companies take advantage of investment opportunities and build their marketing strategies.
Minh Sang VO,Mai Tran NGUYEN,Tuong Vi LE,Gia Bao NGUYEN,My Duyen HO,Thi Phuong Thao PHAM 한국유통과학회 2022 The Journal of Asian Finance, Economics and Busine Vol.9 No.5
Purpose: The is study aimed to examine the impact of consumer ethnocentrism on reasoned action and brand equity on Generation Z in Vietnam. Research design, data and methodology: A quantitative study was undertaken on 302 Generation Z members. The data for the study was collected using a Google Form-based questionnaire from December 2021 to January 2022. Descriptive statistics, Cronbach’s alpha, and structural equation modeling were among the data analysis techniques employed. The results: The results show that consumer ethnocentrism has a direct positive impact on reasoned action (subjective norms and attitude toward domestic goods) as well as an indirect positive impact on brand equity, including brand awareness, brand quality, and brand image. Major findings: According to the findings of this study, governments should continue to push propaganda and advocacy programs, call for national pride and encourage home consumers to support and use domestic goods. Domestic brands must strengthen their ties to the community and invest in community-oriented programs that promote domestic consumption. Vietnam’s domestic fashion brands need to promote the exploitation of community-oriented and nationalistic content to call on domestic consumers to support them to consume domestic brands.
Minh Sang VO,Ngoc Phu TRAN,Thi Kieu Thu NGUYEN,Thi Cam Tien HUYNH,Thi Kim Loi NGUYEN,Le Phuong Nghi THACH,Gia Nhu THAI,Thi Thanh Sang TRAN 한국유통과학회 2022 The Journal of Asian Finance, Economics and Busine Vol.9 No.4
This study intends to analyze the impact of the country of origin on the intention to ingest COVID-19 vaccinations by measuring Vietnamese people’s perceptions of India in the manufacture of COVID-19 vaccines. The research is done using a quantitative method, and primary data was obtained using a conventional manner based on the willingness of the research respondents, who are Vietnamese persons aged 18 and up, to contribute information. The findings revealed that perceived brand association and perceived brand quality directly positively impact the COVID-19 vaccine’s consumption intention and willingness. Meanwhile, while the perceived country image component has no direct effect on consumption intention, it does have a positive indirect effect on consumption intention through perceived brand linkage and perceived brand quality. The findings also emphasize the importance and significance of a country’s image in brand association and quality perception. The study’s findings imply that to increase consumers’ willingness to buy India’s COVID-19 vaccination, the country should develop communication initiatives to improve consumer perceptions of the country’s image, the perceived value of the brand association, and brand quality.
LE, Thai Thanh Dat,HO, Thi Thanh Ngan,LE, Nguyen Truc Quyen,HUYNH, Thi Khanh Tuyen,NGUYEN, Minh Tri,LUU, Thi Mai Anh,HOANG, Thi Phuong Thao,NGUYEN, Trong Luan Korea Distribution Science Association 2022 The Journal of Asian Finance, Economics and Busine Vol.9 No.6
The purpose of the study is to analyze the significant impacts of expectations, performance, complaints, and fairness that affect consumer satisfaction. The methodology involves reviewing and referencing relevant literature carefully, then proposing a model for customer satisfaction. This study is empirically based on a survey with 50 respondents who work in the field of import and export in the region stretching from the north to the south of Vietnam. The sampling method used in this study is the in-depth interview method. The results show that: (1) expectation has a specific impact on customer satisfaction, (2) performance has a positive impact on customer satisfaction, and (3) complaint which is an intermediary factor between expectation, performance, and fairness has an impact on satisfaction, (4) fairness has a positive effect on satisfaction, in addition, fairness is an extremely important feature when customers choose an import-export service. Research implies that increasing expectations, performance, and fairness results in an improved customer experience and satisfaction when they use the service. It is suggested that the complaint factor continue to be studied and looked into because it still has some effect on satisfaction and is an intermediate variable that changes how the other factors relate to each other.
Le Thi Thuy Lien,Nguyen Khoi Viet,Hoang Van Hoa,Phung Bao Ngoc,Nguyen Ngoc Trang,Vu Thi Kim Thoa,Nguyen Cong Tien,Phan Anh Phuong,Pham Minh Thong,Vu Dang Luu 아시아심장혈관영상의학회 2022 Cardiovascular Imaging Asia Vol.6 No.2
Objective: To compare left ventricular (LV) function, ejection fraction (EF), end-diastolic volume (EDV), end-systolic volume (ESV), and regional wall motion analyzed in 256-slice dualsource coronary CT angiography (DSCT) with 2D transthoracic echocardiography (TTE). Materials and Methods: One hundred twelve patients suspected of coronary artery disease underwent DSCT and 2D-TTE within one week for LVEF, EDV, and ESV. The correlation between DSCT and 2D-TTE measurements was analyzed through linear regression and Bland- Altman analysis. Regional wall motion was visually scored with a 3-point scale (1, normal; 2, hypokinesia; 3, dysphagia, akinesia). Results: Average LVEF at 66.45%±1.27% (range 23%–85%) as determined on DSCT compared with 66.09%±1.01% (range 25%–84%) on 2D-TTE. LVEF exhibited a good correlation between DSCT and 2D-TTE (r=0.715; p<0.001). Good correlations between DSCT and 2D-TTE were demonstrated for LVEDV (r=0.732; p<0.001) and LVESV (r=0.841; p<0.001). Mean differences (±SD) of 1.78±24.10 mL (p<0.05) and 0.77±13.70 mL (p<0.05) were observed between DSCT and 2D-TTE for LVEDV and LVESV, respectively. LVEF was slightly overestimated with DSCT (0.52%±9.59%; p<0.05). Although the LVEF values calculated by DSCT and 2D-TTE were similar, EDV and ESV from DSCT were statistically higher than those from 2D-TTE (p<0.05). Agreement between DSCT and 2D-TTE in regional wall motion was 96.4%, κ=0.840. Conclusion: DSCT can provide comparable results to those using 2D-TTE for LV function (EF, EDV, and ESV) and regional wall motion assessment in a heterogeneous population.
Minh-Huy Dinh Dang,Linh Ho Thuy Nguyen,Trang Thi Thu Nguyen,Ngoc Xuan Dat Mai,Phuong Hoang Tran,Tan Le Hoang Doan 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.103 No.-
Functionalized metal–organic frameworks have recently received significant attention in heterogeneouscatalysis applications due to their high catalytic activity. In this work, a sulfate-functionalized Hf-clusterbasedmetal–organic framework was prepared via sulfation of a Hf-MOF, named Hf-BTC, constructed byHf6 clusters and 1,3,5-tricarboxylate linkers. The Hf-BTC-SO4 material was consequently demonstrated tobe an efficiently reusable superacid catalyst for a one-pot three-component reaction of pyrimido[1,2-a]benzimidazoles synthesis. The reaction catalyzed by the sulfated Hf-BTC could be carried out under mildand solvent-free conditions and give superior performance in a wide range of substrates. According todetailed investigation, the good catalytic performance of the sulfated-functionalized MOF likely originatesfrom the high-porosity framework and the high active sites of the functionalized clusters. Importantly, the catalyst could be easy to recover and reuse the functionalized framework several timeswith minor changes in catalytic efficiency.