Computation of transient viscous flows using indirect radial basis function networks

In this paper, an indirect/integrated radial-basis-function network (IRBFN) method is further developed to solve transient partial differential equations (PDEs) governing fluid flow problems. Spatial derivatives are discretized using one- and two-dimensional IRBFN interpolation schemes, whereas temporal derivatives are approximated using a method of lines and a finite-difference technique. In the case of moving interface problems, the IRBFN method is combined with the level set method to capture the evolution of the interface. The accuracy of the method is investigated by considering several benchmark test problems, including the classical lid-driven cavity flow. Very accurate results are achieved using relatively low numbers of data points

The Leadership Competency in Vietnam Public Administration

Globalization and technological development have changed people’s demand, which leads to many challenges for public and private sectors. Public administration can overcome the challenges by reforming their structure and performance. In this research, the authors affirmed the important roles of leaders in public administration. This research used the integrated leadership theory in the context of Vietnam public administration to build a framework of competency for leaders. The Key Informant Panel and the in-depth interview method were implemented to achieve the research objectives. Research findings have built a leadership competency framework for the public sector, which benefits both researchers and practioners. For researchers, the findings can add to leadership competency theories, especially in the public sector. For policy-makers, the findings can be solid foundations which they can rely on to work out policies for leadership development in Vietnam public sector

Insights into the magnetic origin of CunCr (n= 9÷11) clusters: A superposition of magnetic and electronic shells

Interests in Cu-Cr sub-nanometer systems have been increasing due to the recently-found icosahedral Cu12Cr cluster as a superatomic molecule, where the 3d-Cr and 4s-Cu electrons can phenomenologically form the 18-e molecular shell (1S21P61D10) of Cu12Cr. In this report, we set out to investigate the energetically-preferred geometries and stabilities of CunCr (n = 9÷11) clusters using the density-functional-theory calculations. It is found that not all of 3d-Cr electrons involve in the formation of the cluster shell and the remaining localized ones cause the magnetic moment of the clusters, which is different from what was believed

CHARACTERISTICS OF QUATERNARY SEDIMENTARY FACIES IN RELATION TO WATER BEARING CAPACITY OF AQUIFERS AND AQUICLUDES IN RED RIVER DELTA, VIETNAM

Joint Research on Environmental Science and Technology for the Eart

IMPACT OF SEA LEVEL RISE ON COASTAL RESOURCE IN VIETNAM

Joint Research on Environmental Science and Technology for the Eart

Tổng hợp và nghiên cứu hình thái, tính chất của lớp phủ PbO2 kết tủa điện hóa trên nền thép mềm và khả năng ứng dụng làm điện cực trong pin chì dự trữ

Lead dioxide electrodeposition has been caried out at constant currents from lead nitrate solution 0.5 mol/L on mild steel substrate; Fe3O4 films coating on steel substrate that prepared by electrochemical oxidation method (Fe3O4ĐH) and chemical oxidation method (Fe3O4HH)  in hot alkaline solution. The morphology and structure analysis of the PbO2 layers were investigated using scaning electron microscopy (SEM) and X-ray diffraction techniques. PbO2/steel, PbO2/Fe3O4ĐH/steel, PbO2/Fe3O4HH/steel electrodes were tested the electrochemical behaviors with the role of the positive electrodes in Pb/HSiF6/PbO2 reserve battery. When synthesized in the conditions: 0.5 M Pb(NO3)2 solution, the imposed current density from 5 to 40 mA/cm2, temperature 30 °C, pH 4; PbO2 coatings formed on the mild steel substrate mainly with betta-PbO2 crystals of tetrahedral structure with different sizes and tight, solid arrangement. The best adhesion PbO2 coatings had obtained on mild steel substrate with Fe3O4 conversion layer, which formed by electrochemical methods (Fe3O4ĐH). Results of discharge test showed that the stable discharge times at maximum voltage decreased if current density, which was used in electrodeposition of PbO2 increased. In the electrodeposition of PbO2 at imposed current density of 10 mA/cm2, the obtained PbO2/Fe3O4ĐH/steel electrodes have the stable discharge times up to 390 seconds at potentials 1.69-1.7 Volts

So sánh khả năng phóng điện của cặp điện cực Pb-PbO2 trong dung dịch axit metasunfonic và axit floroxilixic

The HBF4 and H2SiF6 acids are often used as electrolyte for lead reserves batteries, but these are relatively durable acids and harmful to the environment. Meanwhile CH3SO3H acid is biodegradable to form sulfate ions (SO42-) and carbon dioxide (CO2) in the natural environment, thus it’s more environmentally friendly. This paper presents the results of using CH3SO3H acid as electrolyte for lead batteries in different temperatures, acid concentrations and rate of number of acid moles/number of PbO2 moles, in comparison to H2SiF6 acid. In the some determined conditions, CH3SO3H acid can be use as an electrolyte for lead reserves batteries.The 30 % CH3SO3H solution, rates of number of acid moles/number of PbO2 moles is 5.0 ​​and the working temperature 20 °C are suitable conditions for using as liquid electrolyte of the reserve battery. While discharging at 30 °C, we received the Ebat. = 1897 mV, the maximum discharge voltage = 1694 mV and discharge time = 251s (with discharge voltages ≥ 1650 mV)

Determinants of organic food purchasing intention: an empirical study of local consumers in Da Nang city, Central Vietnam

With the rapid economic development in the past decades, Vietnamese people are more and more aware of the role of safe food for their health and that of their families. Currently, the trend of organic food consumption is happening faster, especially in urban areas. The study aims to determine the influence of transparent information and knowledge about organic products on consumers' attitudes, trust, and subjective norms affecting their purchase intention of organic products. Data were collected from 420 consumers in Da Nang city, Central Vietnam. Exploratory Factor Analysis (EFA) method and Structural Equation Modeling (SEM) were used to evaluate the scale's reliability and identify the impact factors. The results show that attitudes and trust have a positive relationship with the intention to buy organic food. In addition, research shows that trust is a predecessor of attitudes and mediates the relationship between information, knowledge about organic food, and intention to buy organic food. The study's findings are consistent with previous literature and provide implications for food managers, organic food businesses, and the community

ARSENIC POLLUTION IN TUBE WELL WATER AT HANOI SUBURB VILLAGES

Joint Research on Environmental Science and Technology for the Eart

Ecological and behavioural risk factors of scrub typhus in central Vietnam: a case‑control study

Background: The risk factors for scrub typhus in Vietnam remain unknown. Scrub typhus caused by Orientia tsutsugamushi often presents as an undifferentiated febrile illness and remains under appreciated due to the limited availability of diagnostic tests. This tropical rickettsial illness is increasingly recognized as an important cause of non-malaria acute undifferentiated fever in Asia. This study aimed to investigate behavioural and ecological related risk factors of scrub typhus to prevent this potentially life-threatening disease in Vietnam. Methods: We conducted a clinical hospital-based active surveillance study, and a retrospective residence-enrolment date-age-matched case-control study in Khanh Hoa province, Vietnam, from August 2018 to March 2020. Clinical examinations, polymerase chain reaction and enzyme-linked immunosorbent assay IgM tests were applied to define cases and controls. All enrolled participants filled out a questionnaire including demographic socio-economic status, personal behaviors/protective equipment, habitat connections, land use, and possible exposure to the vector. Multivariable conditional logistic regression was used to define the scrub typhus associated risk factors. Results: We identified 44 confirmed cases and matched them with 152 controls. Among cases and controls, the largest age group was the 41-50 years old and males accounted for 61.4% and 42.8%, respectively. There were similarities in demographic characteristics between the two groups, with the exception of occupation. Several factors were significantly associated with acquisition of scrub typhus, including sitting/laying directly on household floor [adjusted OR (aOR) = 4.9, 95% CI: 1.6-15.1, P = 0.006], household with poor sanitation/conditions (aOR = 7.9, 95% CI: 1.9-32.9, P = 0.005), workplace environment with risk (aOR = 3.0, 95% CI: 1.2-7.6, P = 0.020), always observing mice around home (aOR = 3.7, 95% CI: 1.4-9.9, P = 0.008), and use of personal protective equipment in the field (aOR = 0.4, 95% CI: 0.1-1.1, P = 0.076). Conclusions: Ecological and household hygiene-related factors were more associated with scrub typhus infection,than individual-level exposure activities in the hyper-endemic area. These findings support local education and allow people to protect themselves from scrub typhus, especially in areas with limitations in diagnostic capacit