318 research outputs found

    Degenerate complex Hessian equations on compact K\"ahler manifolds

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    Let (X,ω)(X,\omega) be a compact K\"ahler manifold of dimension nn and fix m∈Nm\in \mathbb{N} such that 1≤m≤n1\leq m \leq n. We prove that any (ω,m)(\omega,m)-sh function can be approximated from above by smooth (ω,m)(\omega,m)-sh functions. A potential theory for the complex Hessian equation is also developed which generalizes the classical pluripotential theory on compact K\"ahler manifolds. We then use novel variational tools due to Berman, Boucksom, Guedj and Zeriahi to study degenerate complex Hessian equations

    Development of a Filament Extruder Using Flow Theory with the Newtonian Fluid Assumption

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    This article presents an investigation of the flow characteristics of the polymer melt in a single-screw extruder and the design of a filament extruder to verify the above theory. The flow characteristics of the polymer melt in a single-screw extruder are likable to that of a viscous liquid between two infinitely parallel sheets, one moving and the other stationary. An integrated flow equation was then found for a case when the viscosity of a liquid remains constant in an isothermal extrusion. These flow behavior theories were then verified via the design and fabrication of a filament extruder for 3D printers

    Development of a Filament Extruder Using Flow Theory with the Newtonian Fluid Assumption

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    This article presents an investigation of the flow characteristics of the polymer melt in a single-screw extruder and the design of a filament extruder to verify the above theory. The flow characteristics of the polymer melt in a single-screw extruder are likable to that of a viscous liquid between two infinitely parallel sheets, one moving and the other stationary. An integrated flow equation was then found for a case when the viscosity of a liquid remains constant in an isothermal extrusion. These flow behavior theories were then verified via the design and fabrication of a filament extruder for 3D printers

    Study of Using Cassava Pulp to Produce Livestock Feed Pellet

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    In Vietnam, the cassava production capacity is about 10 million tons annually. Indeed, it eliminates approximate 4 million tons of cassava pulp from the cassava starch factories. This amount of cassava is usually dried to feed cattle or fertilizer. However, drying of cassava pulp has its disadvantages such as air pollution, difficult storage and transportation. This study has proposed and successfully tested a line of equipment used to produce pellets from the utilization of fresh cassava pulp bringing from cassava starch processing plants. The processing includes a mixing of fresh cassava pulp with dried cassava starch, pressing and drying of pellets. The experiment results show that when the mixing ratio between cassava starch and cassava residue is 1:10 – 1:5, the cassava pulp pellets after drying achieved the required technical specifications. Hence, it has high volume density, the dried specific weight of the pellets is about 700 kg / m3, the breaking strength of the pellets is greater than 2 kG, the tanning time of the pellets is greater than 116 minutes in water, the moisture content of the pellets is remained in 13% after drying in 5-5.5 hours

    Activities of the practice teaching organization and vocational teaching facilities in collaboration between the vocational school and units employing

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    The aim of this research is to evaluate the current level of preparation in the organization of practical training as well as the facilities that are available for practical vocational training. The collaboration in education between businesses and vocational schools is an effective strategy. As a result of the rapid transformation that has taken place in the socioeconomic context for professional skills and practical training among employees, a new educational strategy is required to address these demands in order to meet the needs of the workforce. A quantitative method was applied in this research. There were 570 individuals who were chosen at random. According to the findings, the majority of instructors and technicians possessed regulations for conducting practical teaching activities as well as suitable facilities and equipment for the purpose of vocational training. This study presents a number of suggestions for improving the standard of educational institutions as well as the professional growth opportunities available to teachers and lecturers. In addition, facility management and maintenance as well as optimize the instructional facilities and equipment are required

    Evaluating model teacher education and training at Vietnam's universities of technology and education

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    The traditional educational paradigm has become outdated as a result of changes in both the cultural and socioeconomic setting. A more sustainable and acceptable teacher is needed in education. A quantitative study was conducted. 95 administrators and teachers at the University of Technology and Education participated in this study with the aim of analyzing the current status of the teacher education model at the institution. According to the findings of the study, the model for educator preparation has been put into practice primarily through the processes of planning, organizing and directing activities related to educator preparation as well as inspecting and assessing the quality of education. The outcomes of the study indicate that it is essential to design educational programs that are appropriate for the present context. In particular, the study suggests that one of the most important steps towards achieving success is to incorporate technology into teaching methods. The process of educating teachers with the right degree of expertise and skills should be emphasized by educators and policymakers by developing relationships with other educational institutions and allowing teachers to participate in internships

    Assessing the efficacy of online applications in enhancing classroom teaching: A comprehensive evaluation of execution and effectiveness

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    This study explores the practical application of online applications in innovating the organization of teaching activities within public schools in Hue City, Vietnam. The research investigates the nuanced dynamics of execution and efficiency in using online applications across various teaching categories. The study employs a systematic approach to participant selection using stratified sampling based on geographical criteria to ensure representation from both the northern and southern regions of the city. A total of 192 teacher survey questionnaires were distributed focusing on the execution and efficiency of online applications in categories such as warm-up activities, knowledge building, review and consolidation, practice activities and testing and assessment. The commitment to data quality is demonstrated by the high response rate with 187 valid questionnaires collected (97.3% of the expected sample). Statistical analyses including mean scores, standard deviations and correlation coefficients were employed to provide a comprehensive evaluation of the current state of online application integration in teaching activities. The findings reveal varying levels of execution and efficiency across different teaching categories emphasizing the need for targeted improvement strategies. Strong positive correlations were observed in specific categories such as practice activities highlighting a consistent association between effective execution and efficiency. The study contributes valuable insights to the discourse on technology integration in education, offering recommendations for teachers, administrators and policymakers seeking to optimize the impact of online applications on teaching practices in the Vietnamese educational context

    Optimised cathodic protection design for maximum bond performance in reinforced concrete

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    The influence of the long term effects of impressed current cathodic protection (ICCP) on the bond strength is investigated. A total of 16 pull-out specimens were divided into four series and the steel bars pre-corroded to target degrees of 0 % (control), 1 %, 2 % and 5 % weight loss. Four levels of ICCP current density ranging from approximately 0 (control) to over 1000 µA/cm2 were applied to each series. These are considerably higher than the levels typically used in practice, which rarely exceed 2 µA/cm2, but were used to replicate long term application within a reasonable timescale. Following pull-out tests, the values of bond load were determined. The analysis accounts for the accelerated ICCP by relating the total charge to the steel reinforcement in coulombs (current x time) to the bond values and migration of chloride ions. The results show that although some loss in bond is evident from the ICCP, an optimised current density can be applied to a real structure without affecting the as-designed bond strength in the long term e.g. ≤ 0.65 µA/cm2 for an ICCP duration of 70 years. Application of the same current density reduces the chloride concentration from around the steel irrespective of the degree of corrosion

    Etiology and epidemiology of diarrhea in children in Hanoi, Vietnam

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    SummaryObjectivesThis paper provides a preliminary picture of diarrhea with regards to etiology, clinical symptoms, and some related epidemiologic factors in children less than five years of age living in Hanoi, Vietnam.MethodsThe study population included 587 children with diarrhea and 249 age-matched healthy controls. The identification of pathogens was carried out by the conventional methods in combination with ELISA, immunoseparation, and PCR. The antibiotic susceptibility was determined by MIC following the NCCLS recommendations.ResultsOf those with diarrhea, 40.9% were less than one year old and 71.0% were less than two years old. A potential pathogen was identified in 67.3% of children with diarrhea. They were group A rotavirus, diarrheagenic Escherichia coli, Shigella spp, and enterotoxigenic Bacteroides fragilis, with prevalences of 46.7%, 22.5%, 4.7%, and 7.3%, respectively. No Salmonella spp or Vibrio cholerae were isolated. Rotavirus and diarrheagenic E. coli were predominant in children less than two years of age, while Shigella spp, and enterotoxigenic B. fragilis were mostly seen in the older children. Diarrheagenic E. coli and Shigella spp showed high prevalence of resistance to ampicillin, chloramphenicol, and to trimethoprim/sulfamethoxazole. Children attending the hospitals had fever (43.6%), vomiting (53.8%), and dehydration (82.6%). Watery stool was predominant with a prevalence of 66.4%, followed by mucous stool (21.0%). The mean episodes of stools per day was seven, ranging from two to 23 episodes. Before attending hospitals, 162/587 (27.6%) children had been given antibiotics. Overall, more children got diarrhea in (i) poor families; (ii) families where piped water and a latrine were lacking; (iii) families where mothers washed their hands less often before feeding the children; (iv) families where mothers had a low level of education; (v) families where information on health and sanitation less often reached their households.ConclusionsGroup A rotavirus, diarrheagenic Escherichia coli, Shigella spp, and enterotoxigenic Bacteroides fragilis play an important role in causing diarrhea in children in Hanoi, Vietnam. Epidemiological factors such as lack of fresh water supply, unhygienic septic tank, low family income, lack of health information, and low educational level of parents could contribute to the morbidity of diarrhea in children
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