Parametric Study on Aerodynamic Performance of a Single-stage Transonic Axial Compressor with Recirculation-bleeding Channels

Ky-Quang Pham,Quang-Hai Nguyen,Tien-Dung Vuong,Cong-Truong Dinh 한국유체기계학회 2020 International journal of fluid machinery and syste Vol.13 No.2

This paper investigates a novel casing treatment method, called recirculation-bleeding channels, which combine a recirculation channel with additional bleeding channels. The system consists of 36 channels distributed around the blades and located on rotor shroud surface of a single-stage transonic axial compressor. This study focuses on its effects on aerodynamic performance of a single-stage transonic axial compressor, NASA Stage 37. Validation of numerical model of NASA Stage 37 was performed using experimental data for the single-stage transonic axial compressor. A common drawback of flow recirculation and air bleeding is the reduction in efficiency; however, numerical results showed that with the presence of recirculation-bleeding channels, both stall margin and adiabatic efficiency of the single-stage transonic axial compressor were increased as compared to the smooth casing with small penalty in pressure ratio. A parametric study of the recirculation-bleeding channels was performed for six geometric parameters. With recirculation-bleeding channels, the compressor could reach the stall margin of 13.85% at maximum while still retaining an increase in peak adiabatic efficiency. It is also showed that proper adjustments of the channels design can eliminate the deficiency in pressure ratio at peak efficiency condition.

The Relationship between Corporate Social Responsibility and Customer Purchase Intention: Empirical Evidence from Vietnam

Thang Quang TRAN,Ninh Truong Thi THUY,Dung Viet PHAM 한국유통과학회 2022 The Journal of Asian Finance, Economics and Busine Vol.9 No.5

Corporate social responsibility is becoming increasingly important to organizations, and it has received a lot of attention from the general public and marketing academics. This study aimed to look at the many aspects of corporate social responsibility and see how brand reputation and brand love play a role in the relationship between corporate social responsibility and customer purchase intent. To reach the end, this research applied the theory of social exchange and corporate social responsibility to explain the relationship between the variables. The Partial Least Squares was applied to analyze data collected from survey questionnaires in the Hanoi market (Vietnam) to test the proposed hypothesis. The study resulted in 239 valid survey questionnaires which can be used to test hypotheses by applying SmarPLS software. The results indicated that there are three key elements of corporate social responsibility from customers’ perspectives: responsibility to customers, responsibility to the environment, and responsibility to the community. Interestingly, brand reputation and brand love contribute as mediating roles in the correlation between corporate social responsibility and customer purchase intention. Finally, the authors discussed the findings and the implications of this research in both theoretical and practical aspects, as well as the limitations that future research can focus on.

Exploration of genetic diversity of Bacillus spp. from industrial shrimp ponds in Vietnam by multi-locus sequence typing

Xuan The Le,Dung Tien Pham,Tuan Anh Pham,Tung Thanh Tran,Thanh Huu Khuat,Hoa Quang Le,Ut Ngoc Vu 한국수산과학회 2019 Fisheries and Aquatic Sciences Vol.22 No.3

Bacillus is a diverse genus consisting of more than 200 species with extensive genetic diversity. Their beneficial effects in industrial shrimp farming have been well documented. However, little is known about the biodiversity of the Bacillus spp. in this aquaculture system. Taxonomic analysis by 16S rRNA sequencing does not always allow species-level identification of Bacillus spp. In this study, 26 Bacillus isolates from two industrial Litopenaeus vannamei shrimp ponds in Bac Lieu Province, Vietnam, were analyzed for their genetic diversity by multi-locus sequence typing (MLST). A total of 22 sequence types were identified and segregated into four distinct clusters, corresponding to B. subtilis, B. velezensis, B. siamensis, and B. licheniformis. Bacillus subtilis and B. velezensis accounted for more than 73% of the Bacillus isolates. Notably, the MLST scheme exhibited high discriminatory power and might be further simplified to be a convenient method to identify species of the genus Bacillus.

Oxidize Graphene by UV-Ozone Treatment in Vacuum Chamber

Dinh, S. Thach,Pham, T. H. Nhung,Nguyen, T. T. Hien,Dinh, N. T. Nghia,Vu, V. Quang,Hoang, T. K. Dung,Duong, D. Loc American Scientific Publishers 2016 Journal of nanoscience and nanotechnology Vol.16 No.8

<P>As changing graphene properties is vital to promote it as electronic device, we developed graphene modified method with epoxy group by two simple methods: ultraviolet irradiation with various partial oxygen pressures and ultraviolet irradiation under rich oxygen condition with various temperatures. By Hall measurement, the electric mobility in graphene was decreased with increasing temperature during UV-ozone treatment at 50 degrees C, 80 degrees C, 100 degrees C and 120 degrees C. At low partial oxygen pressure (less than 160 Torr) the oxidation degree is not significant. Additionally, Raman spectroscopy showed the disrupted pi-pi structure in graphene. Based on the above identification we supposed that epoxy group might establish on graphene surface.</P>

Adaptive streaming of audiovisual content using MPEG DASH

Thang, T. C.,Quang-Dung Ho,Jung Won Kang,Pham, A. T. IEEE 2012 IEEE transactions on consumer electronics Vol.58 No.1

<P>HTTP streaming has become a cost effective means for multimedia delivery nowadays. In this paper, we study the use of MPEG DASH standard to stream audiovisual content. We first describe a novel estimation method for connection throughput. Then, employing the extensibility feature of DASH syntax, we present a systematic method for selecting the best audio and video alternatives given the estimated throughput. The experiments show that our solution is stable to short-term fluctuations while responding quickly to large fluctuations.</P>

Exploration of genetic diversity of Bacillus spp. from industrial shrimp ponds in Vietnam by multi-locus sequence typing

Le, Xuan The,Pham, Dung Tien,Pham, Tuan Anh,Tran, Tung Thanh,Khuat, Thanh Huu,Le, Hoa Quang,Vu, Ut Ngoc The Korean Society of Fisheries and Aquatic Scienc 2019 Fisheries and Aquatic Sciences Vol.22 No.8

Bacillus is a diverse genus consisting of more than 200 species with extensive genetic diversity. Their beneficial effects in industrial shrimp farming have been well documented. However, little is known about the biodiversity of the Bacillus spp. in this aquaculture system. Taxonomic analysis by 16S rRNA sequencing does not always allow species-level identification of Bacillus spp. In this study, 26 Bacillus isolates from two industrial Litopenaeus vannamei shrimp ponds in Bac Lieu Province, Vietnam, were analyzed for their genetic diversity by multi-locus sequence typing (MLST). A total of 22 sequence types were identified and segregated into four distinct clusters, corresponding to B. subtilis, B. velezensis, B. siamensis, and B. licheniformis. Bacillus subtilis and B. velezensis accounted for more than 73% of the Bacillus isolates. Notably, the MLST scheme exhibited high discriminatory power and might be further simplified to be a convenient method to identify species of the genus Bacillus.

Novel online routing algorithms for smart people-parcel taxi sharing services

Son Nguyen Van,Nhan Vu Thi Hong,Dung Pham Quang,Hoai Nguyen Xuan,Behrouz Babaki,Anton Dries 한국전자통신연구원 2022 ETRI Journal Vol.44 No.2

Building smart transportation services in urban cities has become a worldwide problem owing to the rapidly increasing global population and the development of Internet-of-Things applications. Traffic congestion and environmental concerns can be alleviated by sharing mobility, which reduces the number of vehicles on the road network. The taxi-parcel sharing problem has been considered as an efficient planning model for people and goods flows. In this paper, we enhance the functionality of a current peopleparcel taxi sharing model. The adapted model analyzes the historical request data and predicts the current service demands. We then propose two novel online routing algorithms that construct optimal routes in real-time. The objectives are to maximize (as far as possible) both the parcel delivery requests and ride requests while minimizing the idle time and travel distance of the taxis. The proposed online routing algorithms are evaluated on instances adapted from real Cabspotting datasets. After implementing our routing algorithms, the total idle travel distance per day was 9.64% to 12.76% lower than that of the existing taxi-parcel sharing method. Our online routing algorithms can be incorporated into an efficient smart shared taxi system.

Management of Antibiotic-Resistant Helicobacter pylori Infection: Perspectives from Vietnam

Vu Van Khien,Duong Minh Thang,Tran Manh Hai,Nguyen Quang Duat,Pham Hong Khanh,Dang Thuy Ha,Tran Thanh Binh,Ho Dang Quy Dung,Tran Thi Huyen Trang,Yoshio Yamaoka 거트앤리버 소화기연관학회협의회 2019 Gut and Liver Vol.13 No.5

Antibiotic resistance is the most important factor leading to the failure of eradication regimens. This review focuses on the prevalence of Helicobacter pylori primary and secondary resistance to clarithromycin, metronidazole, amoxicillin, levofloxacin, tetracycline, and multidrug in Vietnam. We searched the PubMed, EMBASE, Vietnamese National Knowledge Infrastructure, and Vietnamese Biomedical databases from January 2000 to December 2016. The search terms included the following: H. pylori infection, antibiotic (including clarithromycin, metronidazole, amoxicillin, levofloxacin, tetracycline, and multidrug) resistance in Vietnam. The data were summarized in an extraction table and analyzed manually. Finally, Excel 2007 software was used to create charts. Ten studies (three studies in English and seven in Vietnamese) were included in this review. A total of 308, 412, 523, 408, 399, and 268 H. pylori strains were included in this review to evaluate the prevalence of H. pylori primary resistance to amoxicillin, clarithromycin, metronidazole, levofloxacin, tetracycline, and multidrug resistance, respectively. Overall, the primary resistance rates of amoxicillin, clarithromycin, metronidazole, levofloxacin, tetracycline, and multidrug resistance were 15.0%, 34.1%, 69.4%, 27.9%, 17.9% and 48.8%, respectively. Secondary resistance rates of amoxicillin, clarithromycin, metronidazole, levofloxacin, tetracycline, and multidrug resistance were 9.5%, 74.9%, 61.5%, 45.7%, 23.5% and 62.3%, respectively. In Vietnam, primary and secondary resistance to H. pylori is increasing over time and affects the effectiveness of H. pylori eradication.

Determinants Influencing Information Transparency in Vietnamese Commercial Banks

NGUYEN, Minh Phuong,NGUYEN, Thi Hong Hai,HOANG, Phuong Dung,TRAN, Manh Dung,PHAM, Quang Trung Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.12

Information transparency ensures that market players all have the opportunity to access the same information to come up with their assessment of the banks' financial situation, performance and risks to reach effective investment decisions. This research is conducted to investigate the levels of impact of determinants on information transparency by examining the case studies of Vietnamese commercial banks. This study combines both qualitative and quantitative research methods, based on interviews of 32 specialists in banking, accounting and auditing fields, which were conducted to explore determinants influencing information transparency and to develop measurement scales. Then, a survey of 160 managers of commercial banks, audit firms, and accounting managers of firms who frequently had transactions with banks was carried out to investigate the statistical significance of these determinants. The results show that, out of seven determinants that have significant impacts on the banks' information transparency, commitment from banks' senior management regarding transparency in information disclosure has the highest impact, followed by state governance, auditing, information infrastructure, credit rating agencies, personnel and bank performance. Accordingly, we provide some recommendations for improving information transparency in the Vietnamese banking industry context as a case study and in emerging countries context in general.

Pancreaticoduodenectomy with superior mesenteric artery first-approach combined total meso-pancreas excision for periampullary malignancies: A high-volume single-center experience with short-term outcomes

Thanh Khiem Nguyen,Ham Hoi Nguyen,Tuan Hiep Luong,Kim Khue Dang,Van Duy Le,Duc Dung Tran,Van Minh Do,Hong Quang Pham,Hoan My Pham,Thi Lan Tran,Cuong Thinh Nguyen,Hong Son Trinh,Yosuke Inoue 한국간담췌외과학회 2024 Annals of hepato-biliary-pancreatic surgery Vol.28 No.1

Backgrounds/Aims: Pancreaticoduodenectomy (PD) is the only radical treatment for periampullary malignancies. Superior mesenteric artery (SMA) first approach combined with total meso-pancreas (MP) excision was conducted to improve the oncological results. There has not been any previous research of a technique that combines the SMA first approach and total MP excision with a detailed description of the MP macroscopical shape. Methods: We prospectively assessed 77 patients with periampullary malignancies between October 2020 and March 2022 (18 months). All patients had undergone PD with SMA first approach combined total MP excision. The perioperative indications, clinical data, intra-operative index, R0 resection rate of postoperative pathological specimens (especially mesopancreatic margin), postoperative complications, and follow-up results were evaluated. Results: The median operative time was 289.6 min (178−540 min), the median intraoperative blood loss was 209 mL (30−1,600 mL). Microscopically, there were 19 (24.7%) cases with metastatic MP, and five cases (6.5%) with R1-resection of the MP. The number of lymph nodes (LNs) harvested and metastatic LNs were 27.2 (maximum was 74) and 1.8 (maximum was 16), respectively. Some (46.8%) patients had pancreatic fistula, but mostly in grade A, with 7 patients (9.1%) who required re-operations. Some 18.2% of cases developed postoperative refractory diarrhea. The rate of in-hospital mortality was 1.3%. Conclusions: The PD with SMA first approach combined TMpE for periampullary malignancies was effective in achieving superior oncological statistics (rate of MP R0-resection and number of total resected LNs) with non-inferior short-term outcomes. It is necessary to evaluate survival outcomes with long-term follow-up.