Impact of Service Quality Performance on Customer Satisfaction: A Case Study of Vietnam’s Five Star Hotel

To exist in highly competitive market, companies need to pay more attention in improving quality of products and services. It is necessary to maintain customers’ loyalty for sustainable future development. This research focuses on investigating the impact of service quality performance on customer satisfaction in a sample of Vietnam’s five star hotels, with a case study of Hotel X, where service quality is considered as the key to success. This study chose the SERVPERF model as a conceptual framework. Analysis of results shows that components RES-EM, ASSURANCE and RELIABLITY explain customer evaluation of perceived service quality in Hotel X. These components play important roles in service quality measurement and thus it is suggested that five star hotels generally and Hotel X in particular needs to have specific strategies to enhance these components as well as customer satisfaction

Consistency of control performance in 3d overhead cranes under payload mass uncertainty

The paper addresses the problem of effectively and robustly controlling a 3D overhead crane under the payload mass uncertainty, where the control performance is shown to be consistent. It is proposed to employ the sliding mode control technique to design the closed-loop controller due to its robustness, regardless of the uncertainties and nonlinearities of the under-actuated crane system. The radial basis function neural network has been exploited to construct an adaptive mechanism for estimating the unknown dynamics. More importantly, the adaptation methods have been derived from the Lyapunov theory to not only guarantee stability of the closed-loop control system, but also approximate the unknown and uncertain payload mass and weight matrix, which maintains the consistency of the control performance, although the cargo mass can be varied. Furthermore, the results obtained by implementing the proposed algorithm in the simulations show the effectiveness of the proposed approach and the consistency of the control performance, although the payload mass is uncertain. © 2020 by the authors. Licensee MDPI, Basel, Switzerland

Isolation and determination of Vibrio spp. pathogen from Sciaenops ocellatus suffering from hemorrhagic disease under cage culture in Vietnam

This study was carried out to isolate and determine the Vibrio spp. from the Red drum fish (Sciaenops ocellatus) suffering from the hemorrhagic disease in Vietnam.  In this study, 18 strains of Vibrio bacteria were identified from 27 samples of Red drum fish. The isolated bacterial strains were identified with the 16S rRNA sequencing method and checked for morphological, physiological, and biochemical characteristics by using the API 20E KIT. Results of the study revealed the presence of twelve strains of V. alginolyticus, three strains of V. fluvialis, and three strains of V. orientalis. All Vibrio strains have gene similarities with those on the Genbank ranging from 98.05 to 100%. The biochemical characteristics of these 18 isolates were similar and these are susceptible to tetracycline and doxycycline and entirely resistant to ampicillin, amoxicillin, and erythromycin

Một cơ chế quản lý hàng đợi tích cực cải tiến VBLUE trên môi trường truyển video

The rapid development of video streaming applications over the internet poses a growing challenge. The requirements for bandwidth capacity and latency of transmission package often change constantly. One of the queue management mechanisms commonly used to increase the performance and prevent the degradation of video transmission quality is the active queue management mechanism (AQM). However, though the internet is a good effort network it does not have distinctions among transmission packets on the network leading to a significant percentage of video data packet discarded by the network router upon the occurrence of lacking bandwidth on the traffic lines due to congestion. The impact of the lost video package degrading the quality of watching at the receiver may vary from negligible to unacceptable levels. This paper proposes an innovative solution using selected VBLUE to discard the package which is built in the BLUE active queue management mechanism. The simulation results on NS-2 are given to show the efficiency of VBLUE for increasing the significant quality of video streaming.Sự phát triển nhanh chóng các ứng dụng truyền video trên Internet đặt ra những thách thức ngày càng lớn. Các yêu cầu về khả năng băng thông và độ trễ truyền dẫn gói tin thường biến đổi liên tục. Một trong các cơ chế quản lý hàng đợi thường được sử dụng để tăng hiệu năng mạng và ngăn cản sự suy giảm chất lượng truyền video là cơ chế quản lý hàng đợi tích cực (AQM). Tuy nhiên, do mạng Internet là mạng mặc dù được xây dựng với nỗ lực tối đa nhưng chưa thể đảm bảo về QoS (best-effort network) và không có sự phân biệt giữa các gói tin truyền trên mạng dẫn đến tỷ lệ đáng kể các gói dữ liệu video bị loại bỏ bởi các bộ định tuyến mạng khi xảy ra tình trạng thiếu băng thông trên các đường truyền do bị tắc nghẽn. Ảnh hưởng của việc mất gói tin video làm suy giảm chất lượng xem ở phía máy nhận có thể thay đổi từ không đáng kể đến mức không thể chấp nhận được. Bài báo này đề xuất một giải pháp cải tiến VBLUE sử dụng lựa chọn loại bỏ gói tin được tích hợp ngay trong cơ chế hàng đợi tích cực BLUE. Các kết quả mô phỏng trên NS-2 đã cho thấy hiệu quả của VBLUE làm tăng chất lượng phát luồng video một cách đáng kể.  

Verifying the Reliability of Impressed Current Method to Simulate Natural Corrosion in Reinforced Concrete

In order to accelerate the corrosion of steel reinforcement in the reinforced concrete structures for laboratory research, the impressed current method has been used widely regardless of the appropriacy of this method on the various aims of the studies relating to the deterioration of the reinforced concrete structures. The aim of this study is to characterize the influence of the impressed current method on the steel-concrete interface in the reinforced concrete to verify the reliability of this method on simulating the natural corrosion. The mill-scale of the steel reinforcement and the steel-concrete interfacial region were investigated using SEM-EDS. The results indicate that impressed current can induce the non-uniform and localized corrosion on the steel reinforcement. The corrosion products formed were likely to the natural corrosion induced by chloride environments. However, the oxidization of OH- at anode can inhibit the precipitation of corrosion products at steel-concrete interfacial region and then slowing down the formation of crack in concrete. This positively leads to an overestimation of load capacity of corroded structure and raises doubt on utilizing this technique to simulate the corrosion behavior

Determinants of Green Banking Implementation in Emerging Country: Evidence from Vietnam Banks

With the purpose of examining which factors affecting on the implementation of ‘Green Banking’ in transitional countries, the research used in-depth interview and survey questionnaire with statistics analysis with the case of Vietnam banks. The results showed that in emerging country such as Vietnam, the level of ‘Green Banking’ implementation is most affected by Human determinant, followed by Strategy, Product & Services, Culture and Technology determinant respectively. Based on findings, several implications were proposed to enhance the performance of these kind of environment friendly financial products in transitional country. By determining these factors, the banking sector in transitional countries will enhance the implementation of ‘Green Banking’ and achieve sustainable development in the context of escalating environmental contamination. Keywords: Green Banking, Implementation, Emerging Country, Human DOI: 10.7176/EJBM/11-15-04 Publication date:May 31st 201

Analysis of Electromagnetic Parameters of Hybrid Externally Excited Synchronous Motors for Electric Vehicle Applications

This paper presents two different approaches to improve the electromagnetic torque and output power of the hybrid Externally Excited Synchronous Motor (EESM) applied to Electric Vehicles (EVs). An analytical approach is first considered to define the main parameters of the proposed machine. Based on the obtained results from the analytical model, the hybrid EESM is designed with different rotor shapes and step-skewing magnet segments to reduce the total losses and improve torque ripple. Then, Finite Element Analysis (FEA) is applied to compute and simulate electromagnetic parameters, such as the magnetic flux density, mean torque, and output power. The development of these two approaches is validated on an actual EESM machine and the agreement with the theory is shown

An efficient adaptive fuzzy hierarchical sliding mode control strategy for 6 degrees of freedom overhead crane

The paper proposes a new approach to efficiently control a three-dimensional overhead crane with 6 degrees of freedom (DoF). Most of the works proposing a control law for a gantry crane assume that it has five output variables, including three positions of the trolley, bridge, and pulley and two swing angles of the hoisting cable. In fact, the elasticity of the hoisting cable, which causes oscillation in the cable direction, is not fully incorporated into the model yet. Therefore, our work considers that six under-actuated outputs exist in a crane system. To design an efficient controller for the 6 DoF crane, it first employs the hierarchical sliding mode control approach, which not only guarantees stability but also minimizes the sway and oscillation of the overhead crane when it transports a payload to a desired location. Moreover, the unknown and uncertain parameters of the system caused by its actuator nonlinearity and external disturbances are adaptively estimated and inferred by utilizing the fuzzy inference rule mechanism, which results in efficient operations of the crane in real time. More importantly, stabilization of the crane controlled by the proposed algorithm is theoretically proved by the use of the Lyapunov function. The proposed control approach was implemented in a synthetic environment for the extensive evaluation, where the obtained results demonstrate its effectiveness. © 2022 by the authors. Licensee MDPI, Basel, Switzerland

Chemical profile and antibacterial activity of acetone extract of Homalomena cochinchinensis Engl. (Araceae)

Homalomena cochinchinensis Engl. is a rare species which is found in Southern China, Cambodia, Laos and Vietnam and its chemical constituents and bioactivity have not been determined yet. In this study, we identified 32 and 38 compounds in acetone extracts of H. cochinchinensis aerial part and rhizome, respectively via gas chromatography mass spectrometry (GC/MS). The main constituents of acetone extract of the aerial part were 3-((4Z,7Z)-Heptadeca-4,7-dien-1-yl)phenol (18.73%); cis-9,cis-12-Octadecadienoic acid (12.04%); linolenic acid (11.08%); n-Hexadecanoic acid (10.13%); (Z)-3-(Heptadec-10-en-1-yl)phenol (7.09%); ?-Sitosterol (5.58%) and linalool (5.56%). On the other hand, acetone extract of rhizome contained linalool (28.42%); 1,2,3-Propanetriol, 1-acetate (10.13%); 3-((4Z,7Z)-Heptadeca-4,7-dien-1-yl)phenol (5.28%); 3-Buten-2-one, 3-methyl-4-(1,3,3-trimethyl-7-oxabicyclo[4.1.0]heptan-1-yl)- (5.28%) and 4-(2,6,6-Trimethyl-cyclohex-1-enyl)-butyric acid (4.54%). Furthermore, this study has also proved the antibacterial activity of acetone extracts from the aerial part and the rhizome of this species for the first time using disk diffusion method. The results showed that the extract of the aerial part could inhibit the growth of 5 out of a total 6 bacterial strains, including Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, Salmonella enteritidis and Staphylococcus aureus; while the susceptible strains to the rhizome extract were 5 strains, such as B. cereus, E. coli, P. aeruginosa, Salmonella typhimurium and S. aureus. The findings suggest the further application of this species in pharmacology and medicine